Separation of the Acid-sugar Mixtures by Using Acid Retardation and further Concentration of the Eluents by Using Continuous-effect Membrane Distillationhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4692Separation of the Acid-sugar Mixtures by Using Acid Retardation and further Concentration of the Eluents by Using Continuous-effect Membrane DistillationJianjun Liu, Yingjie Qin, Pingli Li, Kunming Zhang, Qing Liu, Liqiang Liu2015-03-30T05:05:56.123043-05:00doi:10.1002/jctb.4692John Wiley & Sons, Inc.10.1002/jctb.4692http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4692Research Articlen/an/aAbstract

BACKGROUND

A major cost in acid-catalysed hydrolysis of biomass to fermentable sugars is the consumption of acid itself. In this study, a combined process was developed, in which the acid and sugar in the hydrolysate were separated by using acid retardation process and then the dilute aqueous product streams were concentrated by using continuous-effect membrane distillation (CEMD) process, thus acid could be reused as a catalyst.

RESULTS

The recovery rate of sugar was as high as 94.3% ~ 99.2% while the recovery rate of sulfuric acid was 92.4% ~ 98.9%. The eluents were further concentrated by using CEMD process. When a solution of 2 wt% sulfuric acid was concentrated up to ca. 40 wt%, the maximum value of permeation flux (Jw) and gained output ratio (GOR) was 6.20 L/(m2h) and 15.50, respectively. Meanwhile, the dilute aqueous sugar solution obtained from corn stover could be concentrated 20-fold to a final concentration of ca. 497.6 g/L by using CEMD process with a final GOR of 5.5.

CONCLUSION

The combination of acid retardation and CEMD processes is suitable for the production of sugar, further purification and concentration of eluents, the sugar solution can be used for fermentation and acid solution can be reused as a catalyst.

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BACKGROUND
A major cost in acid-catalysed hydrolysis of biomass to fermentable sugars is the consumption of acid itself. In this study, a combined process was developed, in which the acid and sugar in the hydrolysate were separated by using acid retardation process and then the dilute aqueous product streams were concentrated by using continuous-effect membrane distillation (CEMD) process, thus acid could be reused as a catalyst.
RESULTS
The recovery rate of sugar was as high as 94.3% ~ 99.2% while the recovery rate of sulfuric acid was 92.4% ~ 98.9%. The eluents were further concentrated by using CEMD process. When a solution of 2 wt% sulfuric acid was concentrated up to ca. 40 wt%, the maximum value of permeation flux (Jw) and gained output ratio (GOR) was 6.20 L/(m2h) and 15.50, respectively. Meanwhile, the dilute aqueous sugar solution obtained from corn stover could be concentrated 20-fold to a final concentration of ca. 497.6 g/L by using CEMD process with a final GOR of 5.5.
CONCLUSION
The combination of acid retardation and CEMD processes is suitable for the production of sugar, further purification and concentration of eluents, the sugar solution can be used for fermentation and acid solution can be reused as a catalyst.
Molecular thermodynamics of soft self-assembling structures for engineering applications†http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4693Molecular thermodynamics of soft self-assembling structures for engineering applications†Alexey Victorov2015-03-30T05:04:38.753304-05:00doi:10.1002/jctb.4693John Wiley & Sons, Inc.10.1002/jctb.4693http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4693Mini Reviewn/an/aABSTRACT

Controlling self-assembly is a key issue in many applications such as encapsulation of drugs, micelle separation, and fabrication of nanoporous materials. For providing guidance to control self-assembly, a reliable prognosis of aggregation behavior is indispensable. Molecular thermodynamic models have been developed for different types of soft mesoscale structures formed by aggregating chainlike amphiphilic molecules. Examples include nonionic and ionic copolymer gels swelling in selective solvents, surfactant micellar solutions and amphiphilic membranes. Though rather different in chemical nature and applications, these systems are all characterized by self-assembly into soft mesoscale structures that are sensitive to external conditions or applied stimuli. The models predict a number of thermodynamic and structural characteristics (equilibrium size and stability of different morphologies, equilibrium swelling, elastic properties, solute partitioning, etc.) in terms of several adjustable parameters and molecular characteristics of components. Consideration of nanoscale morphology gives rise to interesting structure–property relations reflected by relatively simple models. New findings help estimating how variations of controllable factors such as pH, salinity and additives affect self-assembly patterns and aggregate's properties. We discuss recent advances in the development of molecular thermodynamic aggregation models, factors restricting implementation of these models and trends in the field.

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Controlling self-assembly is a key issue in many applications such as encapsulation of drugs, micelle separation, and fabrication of nanoporous materials. For providing guidance to control self-assembly, a reliable prognosis of aggregation behavior is indispensable. Molecular thermodynamic models have been developed for different types of soft mesoscale structures formed by aggregating chainlike amphiphilic molecules. Examples include nonionic and ionic copolymer gels swelling in selective solvents, surfactant micellar solutions and amphiphilic membranes. Though rather different in chemical nature and applications, these systems are all characterized by self-assembly into soft mesoscale structures that are sensitive to external conditions or applied stimuli. The models predict a number of thermodynamic and structural characteristics (equilibrium size and stability of different morphologies, equilibrium swelling, elastic properties, solute partitioning, etc.) in terms of several adjustable parameters and molecular characteristics of components. Consideration of nanoscale morphology gives rise to interesting structure–property relations reflected by relatively simple models. New findings help estimating how variations of controllable factors such as pH, salinity and additives affect self-assembly patterns and aggregate's properties. We discuss recent advances in the development of molecular thermodynamic aggregation models, factors restricting implementation of these models and trends in the field.
Nutrient removal from biogas slurry and biogas upgrading of crude biogas at high CO2 concentrations using marine microalgaehttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4694Nutrient removal from biogas slurry and biogas upgrading of crude biogas at high CO2 concentrations using marine microalgaeYongjun Zhao, Zhigang Ge, Hui Zhang, Jiqing Bao, Shiqing Sun2015-03-30T05:02:38.032345-05:00doi:10.1002/jctb.4694John Wiley & Sons, Inc.10.1002/jctb.4694http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4694Research Articlen/an/aAbstract

BACKGROUND

This study aims to simultaneously reduce biogas slurry nutrient and upgrade biogas via microalgal production. Marine microalgae were grown in a culture medium containing a mixture of seawater and biogas slurry with CO2 from synthetic biogas. The effects of different ratios of biogas slurry and various influent concentrations of CH4 in synthetic biogas on the growth of Nannochloropsis sp. were examined. Nutrient removal and biogas upgrading were also studied under different influent CH4 concentrations.

RESULTS

Nannochloropsis sp. showed optimal growth in 40% biogas slurry and significantly enhanced growth in synthetic biogas with 50% CO2. The optimal range of influent CH4 concentration for the removal of biogas slurry nutrients was 45% to 50%. Notably, the influent CH4 concentration of 60% (v/v) provided an optimal CO2 concentration for Nannochloropsis sp. cultivation. Advantageous CO2 removal and biogas upgrading were observed under this condition. This treatment increased CH4 concentration in synthetic biogas from 60% to 93.58% after 6 d of cultivation.

CONCLUSION

Appropriate control of the biogas slurry or seawater and CH4 concentrations in the influent is crucial to simultaneously optimize nutrient removal and biogas upgrading.

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BACKGROUND
This study aims to simultaneously reduce biogas slurry nutrient and upgrade biogas via microalgal production. Marine microalgae were grown in a culture medium containing a mixture of seawater and biogas slurry with CO2 from synthetic biogas. The effects of different ratios of biogas slurry and various influent concentrations of CH4 in synthetic biogas on the growth of Nannochloropsis sp. were examined. Nutrient removal and biogas upgrading were also studied under different influent CH4 concentrations.
RESULTS
Nannochloropsis sp. showed optimal growth in 40% biogas slurry and significantly enhanced growth in synthetic biogas with 50% CO2. The optimal range of influent CH4 concentration for the removal of biogas slurry nutrients was 45% to 50%. Notably, the influent CH4 concentration of 60% (v/v) provided an optimal CO2 concentration for Nannochloropsis sp. cultivation. Advantageous CO2 removal and biogas upgrading were observed under this condition. This treatment increased CH4 concentration in synthetic biogas from 60% to 93.58% after 6 d of cultivation.
CONCLUSION
Appropriate control of the biogas slurry or seawater and CH4 concentrations in the influent is crucial to simultaneously optimize nutrient removal and biogas upgrading.
Effect of membrane and process characteristics on cost and energy usage for separating alcohol-water mixtures using hybrid vapor stripping-vapor permeation processhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4695Effect of membrane and process characteristics on cost and energy usage for separating alcohol-water mixtures using hybrid vapor stripping-vapor permeation processLeland M. Vane, Franklin R. Alvarez2015-03-30T04:58:31.35995-05:00doi:10.1002/jctb.4695John Wiley & Sons, Inc.10.1002/jctb.4695http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4695Research Articlen/an/aABSTRACT

BACKGROUND

Alcohols, including ethanol and butanol, are receiving increased attention as renewable liquid biofuels. Alcohol concentrations may be low in a biological process due to product inhibition and, for non-starch feedstocks, limited substrate concentrations. The result is high separation energy demand by conventional distillation scenarios, despite favorable vapor-liquid equilibrium and, for butanol, partial miscibility with water. A hybrid vapor stripping-vapor permeation process, termed Membrane Assisted Vapor Stripping (MAVS), incorporating a fractional condensation step were found to be at least 65% more energy efficient than conventional distillation approaches. The effect of process design, component performance, and capacity changes on the energy usage and processing cost of MAVS systems for separating ethanol, 1-butanol, and acetone/butanol/ethanol (ABE) mixtures from water was studied.

RESULTS

For the recovery of 1-butanol from a 1 wt% aqueous solution, the 99.5 wt% 1-butanol product contained 7.0 times as much heating value energy as the MAVS process required to recover and dry it. The calculated cost to perform this separation was 0.126 US$/kg-product (0.102 US$/L) for a heating value cost of 3.69 US$/GJ, far below the current values for crude oil and conventionally-produced ethanol. Energy (electricity, natural gas) was 23% of this cost. The largest capital cost item was the compressor on the overhead vapor stream from the stripping column. Capital costs for membranes/modules was the 6th highest cost category, representing only 4% of the capital cost. A 10-fold increase in membrane cost caused the cost of production to increase 38%.

CONCLUSION

Hybrid MAVS processes are an energy- and cost-efficient means to recover alcohols from water. Despite recent fluctuations, fossil fuel costs are projected to increase. Thus processes utilizing mechanical energy to recapture and transfer thermal energy, including MAVS, should have a greater cost advantage in the future.

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BACKGROUND
Alcohols, including ethanol and butanol, are receiving increased attention as renewable liquid biofuels. Alcohol concentrations may be low in a biological process due to product inhibition and, for non-starch feedstocks, limited substrate concentrations. The result is high separation energy demand by conventional distillation scenarios, despite favorable vapor-liquid equilibrium and, for butanol, partial miscibility with water. A hybrid vapor stripping-vapor permeation process, termed Membrane Assisted Vapor Stripping (MAVS), incorporating a fractional condensation step were found to be at least 65% more energy efficient than conventional distillation approaches. The effect of process design, component performance, and capacity changes on the energy usage and processing cost of MAVS systems for separating ethanol, 1-butanol, and acetone/butanol/ethanol (ABE) mixtures from water was studied.
RESULTS
For the recovery of 1-butanol from a 1 wt% aqueous solution, the 99.5 wt% 1-butanol product contained 7.0 times as much heating value energy as the MAVS process required to recover and dry it. The calculated cost to perform this separation was 0.126 US$/kg-product (0.102 US$/L) for a heating value cost of 3.69 US$/GJ, far below the current values for crude oil and conventionally-produced ethanol. Energy (electricity, natural gas) was 23% of this cost. The largest capital cost item was the compressor on the overhead vapor stream from the stripping column. Capital costs for membranes/modules was the 6th highest cost category, representing only 4% of the capital cost. A 10-fold increase in membrane cost caused the cost of production to increase 38%.
CONCLUSION
Hybrid MAVS processes are an energy- and cost-efficient means to recover alcohols from water. Despite recent fluctuations, fossil fuel costs are projected to increase. Thus processes utilizing mechanical energy to recapture and transfer thermal energy, including MAVS, should have a greater cost advantage in the future.
Evaluation of deep eutectic solvents as co-solvent for steroids 1-en-dehydrogenation biotransformation by Arthrobacter simplexhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4691Evaluation of deep eutectic solvents as co-solvent for steroids 1-en-dehydrogenation biotransformation by Arthrobacter simplexShuhong Mao, Lu Yu, Shaoxian Ji, Xiaoguang Liu, Fuping Lu2015-03-30T04:41:55.361751-05:00doi:10.1002/jctb.4691John Wiley & Sons, Inc.10.1002/jctb.4691http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4691Research Articlen/an/aAbstract

BACKGROUND

As a low-cost alternative to the traditional ionic liquids (ILs), deep eutectic solvents (DESs) have currently attracted increasing attention for its various applications including biocatalysis. This study aimed at analyzing the effect of DESs as ‘green solvents’ on biotransformation in Arthrobacter simplex mediated △1, 2-dehydrogeneration of cortisone acetate (CA) to produce prednisone acetate (PA).

RESULTS

Of the three DESs examined, ChCl:U, as co-solvent was successfully employed as co-solvent to improve the bioconversion efficiency. For substrate feeding concentration of 5 g L−1, the substrate conversion reached up to 93% by immobilized A. simplex cells (4 gDW L−1) and ChCl:U content of 6%, which is more efficient than those without DESs. Importantly, it has been shown that DESs and the immobilized cells can be easily recovered and then reused for five batches of bioconversion with a final conversion above 80%.

CONCLUSION

Our results displayed the potential use of DESs-based systems in industrial steroid biodehydrogenation by A. simplex, and provided an environmentally benign means of steroid biotransformation.

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BACKGROUND
As a low-cost alternative to the traditional ionic liquids (ILs), deep eutectic solvents (DESs) have currently attracted increasing attention for its various applications including biocatalysis. This study aimed at analyzing the effect of DESs as ‘green solvents’ on biotransformation in Arthrobacter simplex mediated △1, 2-dehydrogeneration of cortisone acetate (CA) to produce prednisone acetate (PA).
RESULTS
Of the three DESs examined, ChCl:U, as co-solvent was successfully employed as co-solvent to improve the bioconversion efficiency. For substrate feeding concentration of 5 g L−1, the substrate conversion reached up to 93% by immobilized A. simplex cells (4 gDW L−1) and ChCl:U content of 6%, which is more efficient than those without DESs. Importantly, it has been shown that DESs and the immobilized cells can be easily recovered and then reused for five batches of bioconversion with a final conversion above 80%.
CONCLUSION
Our results displayed the potential use of DESs-based systems in industrial steroid biodehydrogenation by A. simplex, and provided an environmentally benign means of steroid biotransformation.
Purification and characterization of an alkaliphilic endo-xylanase from Streptomyces althioticus LMZM and utilization in pulp industryhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4690Purification and characterization of an alkaliphilic endo-xylanase from Streptomyces althioticus LMZM and utilization in pulp industryLing Luo, Jun Cai, Changgao Wang, Jianguo Lin, Xin Du, Ansheng Zhou, Mengxiong Xiang2015-03-26T03:17:13.426164-05:00doi:10.1002/jctb.4690John Wiley & Sons, Inc.10.1002/jctb.4690http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4690Research Articlen/an/aAbstract

BACKGROUND

Xylanase is the key enzyme involved in the conversion of lignocelluloses.

RESULTS

An extracellular xylanase from Streptomyces althioticus LMZM submerged culture medium using corncob was purified and characterized. The enzyme was purified to 12.65 fold through ammonium sulphate precipitation, Sephadex G-25, DEAE cellulose chromatography and followed by gel filtration through Sephadex G–100 column. The molecular mass of purified xylanase was about 31.75 kDa. The enzyme was an endo-xylanase, as it degraded xylan to xylooligosaccharide with non xylose after 24 hours. The purified enzyme showed optimum activity at 60 °C and at pH 8.0 with a wide range of pH (6.0–11.0) and temperature (40–80 °C). And it was 98.72% and 69.50% residual enzyme activity at pH8.0 and at 60 °C after 1 h. The Km and Vmax values were found to be 43.03 mg/mL and 312.5 µmol/(min · mg), respectively. The enzyme had been remarkably activated by cysteine and Cu2+, and its activity was strongly inhibited by Hg2+. Moreover the brightness of kraft was improved by this xylanase.

CONCLUSION

Since the enzyme was active over wide range of pH, high temperature with remained active, it could find potential uses in biobleaching process in pulp paper industries and production of xylooligosacaharides.

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BACKGROUND
Xylanase is the key enzyme involved in the conversion of lignocelluloses.
RESULTS
An extracellular xylanase from Streptomyces althioticus LMZM submerged culture medium using corncob was purified and characterized. The enzyme was purified to 12.65 fold through ammonium sulphate precipitation, Sephadex G-25, DEAE cellulose chromatography and followed by gel filtration through Sephadex G–100 column. The molecular mass of purified xylanase was about 31.75 kDa. The enzyme was an endo-xylanase, as it degraded xylan to xylooligosaccharide with non xylose after 24 hours. The purified enzyme showed optimum activity at 60 °C and at pH 8.0 with a wide range of pH (6.0–11.0) and temperature (40–80 °C). And it was 98.72% and 69.50% residual enzyme activity at pH8.0 and at 60 °C after 1 h. The Km and Vmax values were found to be 43.03 mg/mL and 312.5 µmol/(min · mg), respectively. The enzyme had been remarkably activated by cysteine and Cu2+, and its activity was strongly inhibited by Hg2+. Moreover the brightness of kraft was improved by this xylanase.
CONCLUSION
Since the enzyme was active over wide range of pH, high temperature with remained active, it could find potential uses in biobleaching process in pulp paper industries and production of xylooligosacaharides.
The prediction and recovery of the flux of PVDF membrane during dead-end microfiltrationhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4688The prediction and recovery of the flux of PVDF membrane during dead-end microfiltrationZhongya Zhu, Yuenan Zhou, Zhan Wang, Ximing Zhang, Kui Gao, Liping Liu, Lina Cheng2015-03-23T09:28:51.540389-05:00doi:10.1002/jctb.4688John Wiley & Sons, Inc.10.1002/jctb.4688http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4688Research Articlen/an/aAbstract

BACKGROUND

This research focused on the fouling behavior of 0.1 µm PVDF membrane caused by activated sludge suspension in dead-end filtration mode and the chemical cleaning of the fouled PVDF membrane by alkaline solutions. A combined intermediate pore blockage and cake filtration model was established to describe flux decline behavior. A series of experiments were performed to validate the proposed model and explore the impacts of operation conditions on the flux decline and recovery.

RESULTS

The flux decline was much faster with the rising transmembrane pressure (TMP) and concentration of mixed liquor suspended solid (MLSS). The proposed model predictions in this paper showed better agreement with the experimental data. Moreover, the cleaning effect of sodium hypochlorite solution was superior to that of sodium hydroxide solution. Temperature was the dominant factor which affected the flux recovery in cleaning operation and the optimum chemical cleaning operation conditions were as follows: CNaOCl= 1%, r = 300 rpm, t = 30 min, T = 318 K.

CONCLUSIONS

The combined model was valid in predicting the flux decline process and more accurate than the classical fouling models under the same operation conditions. The flux recovery got evident improvement under optimized cleaning conditions.

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BACKGROUND
This research focused on the fouling behavior of 0.1 µm PVDF membrane caused by activated sludge suspension in dead-end filtration mode and the chemical cleaning of the fouled PVDF membrane by alkaline solutions. A combined intermediate pore blockage and cake filtration model was established to describe flux decline behavior. A series of experiments were performed to validate the proposed model and explore the impacts of operation conditions on the flux decline and recovery.
RESULTS
The flux decline was much faster with the rising transmembrane pressure (TMP) and concentration of mixed liquor suspended solid (MLSS). The proposed model predictions in this paper showed better agreement with the experimental data. Moreover, the cleaning effect of sodium hypochlorite solution was superior to that of sodium hydroxide solution. Temperature was the dominant factor which affected the flux recovery in cleaning operation and the optimum chemical cleaning operation conditions were as follows: CNaOCl= 1%, r = 300 rpm, t = 30 min, T = 318 K.
CONCLUSIONS
The combined model was valid in predicting the flux decline process and more accurate than the classical fouling models under the same operation conditions. The flux recovery got evident improvement under optimized cleaning conditions.
Fatty acid profile and lipid content of Cylindrotheca closterium cultivated in air-lift photobioreactorhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4687Fatty acid profile and lipid content of Cylindrotheca closterium cultivated in air-lift photobioreactorZeliha Demirel, Esra Imamoglu, Meltem Conk Dalay2015-03-20T05:59:34.619236-05:00doi:10.1002/jctb.4687John Wiley & Sons, Inc.10.1002/jctb.4687http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4687Research Articlen/an/aAbstract

BACKGROUND

The aim of this study was to investigate of how the synergistic protocols between nutrient and light affect the cell growth and lipid content and fatty acid profile of Cylindrotheca closterium. Furthermore, the flow hydrodynamics of a laboratory scale internal loop air-lift photobioreactor were investigated for the cultivation of C. closterium.

RESULTS

Maximum lipid productivity of 140.271 mg/L/d, which corresponded to the maximum biomass production of 0.356 g/L, was obtained in F/2 medium under the light intensity of 56 μE m−2 s−1, highlighting the importance of high biomass accumulation for efficient lipid production. The most abundant saturated and monounsaturated fatty acids were pentadecanoic acid (C15:0) and palmitoleic acid (C16:1) which constituted 16–45% and 17–35% of total fatty acids for all growth conditions, respectively.

CONCLUSION

Palmitoleic acid was the dominant monounsaturated fatty acid, followed by oleic acid, whereas the most abundant saturated fatty acids were pentadecanoic acid and palmitic acid for C. closterium. Another notable outcome was the fatty acid content increased in N-free medium under low light intensity, while nitrogen starvation did not affect the fatty acid content under high light intensity.

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BACKGROUND
The aim of this study was to investigate of how the synergistic protocols between nutrient and light affect the cell growth and lipid content and fatty acid profile of Cylindrotheca closterium. Furthermore, the flow hydrodynamics of a laboratory scale internal loop air-lift photobioreactor were investigated for the cultivation of C. closterium.
RESULTS
Maximum lipid productivity of 140.271 mg/L/d, which corresponded to the maximum biomass production of 0.356 g/L, was obtained in F/2 medium under the light intensity of 56 μE m−2 s−1, highlighting the importance of high biomass accumulation for efficient lipid production. The most abundant saturated and monounsaturated fatty acids were pentadecanoic acid (C15:0) and palmitoleic acid (C16:1) which constituted 16–45% and 17–35% of total fatty acids for all growth conditions, respectively.
CONCLUSION
Palmitoleic acid was the dominant monounsaturated fatty acid, followed by oleic acid, whereas the most abundant saturated fatty acids were pentadecanoic acid and palmitic acid for C. closterium. Another notable outcome was the fatty acid content increased in N-free medium under low light intensity, while nitrogen starvation did not affect the fatty acid content under high light intensity.
The synthesis of new coke-resistant support and its application in propane dehydrogenation to propenehttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4686The synthesis of new coke-resistant support and its application in propane dehydrogenation to propeneShijian Zhou, Yuming Zhou, Yiwei Zhang, Xiaoli Sheng, Zewu Zhang2015-03-20T05:55:40.975916-05:00doi:10.1002/jctb.4686John Wiley & Sons, Inc.10.1002/jctb.4686http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4686Articlen/an/aAbstract

Background

ZSM-5 zeolite has been used as a common support for PtSn-based catalyst in the propane dehydrogenation reaction. But due to its large acidities, the coke accommodation and the stability of the catalyst would not be satisfied. Here, in order to improve these performances, the new hierarchical-porous ZSM-5 (abbreviated henceforth as ZQ) has been synthesized.

Results

By the appearance of hierarchical-pores in ZQ, the pore structure was changed, the acid content was decreased, and the surface properties were promoted. Besides, these modifications on zeolite greatly improved the capacity of catalysts to accommodate coke. Moreover, the coke deposit on PtSnNa/ZQ would migrate from active metal to the support. As expected, for the catalyst of PtSnNa/ZQ, the catalytic performance of propane dehydrogenation to propene and the stability of the catalyst were significantly promoted.

Conclusions

The new hierarchical-porous ZSM-5 support (ZQ) exhibits the enhanced capacity to accommodate coke, and PtSnNa/ZQ possessed better propane conversion and stability of catalyst.

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Background
ZSM-5 zeolite has been used as a common support for PtSn-based catalyst in the propane dehydrogenation reaction. But due to its large acidities, the coke accommodation and the stability of the catalyst would not be satisfied. Here, in order to improve these performances, the new hierarchical-porous ZSM-5 (abbreviated henceforth as ZQ) has been synthesized.
Results
By the appearance of hierarchical-pores in ZQ, the pore structure was changed, the acid content was decreased, and the surface properties were promoted. Besides, these modifications on zeolite greatly improved the capacity of catalysts to accommodate coke. Moreover, the coke deposit on PtSnNa/ZQ would migrate from active metal to the support. As expected, for the catalyst of PtSnNa/ZQ, the catalytic performance of propane dehydrogenation to propene and the stability of the catalyst were significantly promoted.
Conclusions
The new hierarchical-porous ZSM-5 support (ZQ) exhibits the enhanced capacity to accommodate coke, and PtSnNa/ZQ possessed better propane conversion and stability of catalyst.
Polyhydroxyalkanoates, a family of natural polymers, and their applications in drug deliveryhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4685Polyhydroxyalkanoates, a family of natural polymers, and their applications in drug deliveryRinat Nigmatullin, Peter Thomas, Barbara Lukasiewicz, Hima Puthussery, Ipsita Roy2015-03-19T11:29:51.940123-05:00doi:10.1002/jctb.4685John Wiley & Sons, Inc.10.1002/jctb.4685http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4685Reviewn/an/aAbstract

Polyhydroxyalkanoates (PHAs) are natural biopolymers produced by various microorganisms as a reserve of carbon and energy. PHA synthesis generally occurs during fermentation under nutrient limiting conditions with excess carbon. There are two main types of PHAs, short chain length PHAs (scl-PHAs) and medium chain length PHAs (mcl-PHAs). The mechanical and thermal properties of PHAs depend mainly on the number of carbons in the monomer unit and its molecular weight. PHAs are promising materials for biomedical applications because they are biodegradable, non-toxic and biocompatible. The large range of PHAs, along with their varying physical properties and high biocompatibility, make them highly attractive biomaterials for use in drug delivery. They can be used to produce tablets, micro- and nanoparticles as well as drug eluting scaffolds. A large range of different PHAs have been explored and the results obtained suggest that PHAs are excellent candidates for controlled and targeted drug delivery systems.

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Polyhydroxyalkanoates (PHAs) are natural biopolymers produced by various microorganisms as a reserve of carbon and energy. PHA synthesis generally occurs during fermentation under nutrient limiting conditions with excess carbon. There are two main types of PHAs, short chain length PHAs (scl-PHAs) and medium chain length PHAs (mcl-PHAs). The mechanical and thermal properties of PHAs depend mainly on the number of carbons in the monomer unit and its molecular weight. PHAs are promising materials for biomedical applications because they are biodegradable, non-toxic and biocompatible. The large range of PHAs, along with their varying physical properties and high biocompatibility, make them highly attractive biomaterials for use in drug delivery. They can be used to produce tablets, micro- and nanoparticles as well as drug eluting scaffolds. A large range of different PHAs have been explored and the results obtained suggest that PHAs are excellent candidates for controlled and targeted drug delivery systems.
Poly-3-hydroxybutyrate production by Azotobacter vinelandii strains in batch cultures at different oxygen transfer rateshttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4684Poly-3-hydroxybutyrate production by Azotobacter vinelandii strains in batch cultures at different oxygen transfer ratesAlvaro Díaz-Barrera, Rodrigo Andler, Irene Martínez, Carlos Peña2015-03-19T11:26:37.679006-05:00doi:10.1002/jctb.4684John Wiley & Sons, Inc.10.1002/jctb.4684http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4684Research Articlen/an/aABSTRACT

BACKGROUND

Poly-3-hydroxybutyrate (PHB) is a polyester that can be accumulated by Azotobacter vinelandii. This polymer is a biodegradable thermoplastic material used for producing plastics for packaging, biobased films, and biocompatible implants.

RESULTS

PHB produced by wild-type A. vinelandii and a mutant OP strain were evaluated at different agitation rates. The oxygen transfer rate (OTR) evolution was characterized in cultures grown at 300, 400, 500 and 600 rpm, showing for first time the OTR evolution in cultures of mutant OP. Under the conditions evaluated, the cultures were limited by oxygen. In the cultures grown with the OP strain, lower OTR and specific oxygen uptake rate were obtained, indicating a lower necessity of oxygen for growth in this mutant. A higher amount of PHB can be produced by decreasing the OTR. A maximum PHB of 79% on dry weight was observed in the cultures with the wild-type strain, whereas the highest PHB productivity (0.18 g L−1 h−1) was obtained in cultures of A. vinelandii OP conducted at 600 rpm.

CONCLUSION

The amount of PHB produced during the period of oxygen limitation can be controlled by the OTR, opening the possibility to evaluate this parameter as a criterion for scaling-up PHB production by A. vinelandii.

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BACKGROUND
Poly-3-hydroxybutyrate (PHB) is a polyester that can be accumulated by Azotobacter vinelandii. This polymer is a biodegradable thermoplastic material used for producing plastics for packaging, biobased films, and biocompatible implants.
RESULTS
PHB produced by wild-type A. vinelandii and a mutant OP strain were evaluated at different agitation rates. The oxygen transfer rate (OTR) evolution was characterized in cultures grown at 300, 400, 500 and 600 rpm, showing for first time the OTR evolution in cultures of mutant OP. Under the conditions evaluated, the cultures were limited by oxygen. In the cultures grown with the OP strain, lower OTR and specific oxygen uptake rate were obtained, indicating a lower necessity of oxygen for growth in this mutant. A higher amount of PHB can be produced by decreasing the OTR. A maximum PHB of 79% on dry weight was observed in the cultures with the wild-type strain, whereas the highest PHB productivity (0.18 g L−1 h−1) was obtained in cultures of A. vinelandii OP conducted at 600 rpm.
CONCLUSION
The amount of PHB produced during the period of oxygen limitation can be controlled by the OTR, opening the possibility to evaluate this parameter as a criterion for scaling-up PHB production by A. vinelandii.
Optimal design and plantwide control of novel processes for di-n-pentyl ether productionhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4683Optimal design and plantwide control of novel processes for di-n-pentyl ether productionCostin Sorin Bildea, Romuald Győrgy, Eduardo Sánchez-Ramírez, Juan José Quiroz-Ramírez, Juan Gabriel Segovia Hernandez, Anton A. Kiss2015-03-16T02:24:54.82177-05:00doi:10.1002/jctb.4683John Wiley & Sons, Inc.10.1002/jctb.4683http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4683Research Articlen/an/aAbstract

Background

Di-n-pentyl ether (DNPE) is a good candidate for diesel fuel formulations due to its blending cetane number, good cold flow properties and effectiveness in reducing diesel exhaust emissions, particulates and smokes. However, novel processes are required in order to drive the production costs down and to increase the efficiency at industrial scale.

Results

The dehydration of 1-pentanol to yield DNPE is catalyzed by thermally stable resins, such as Amberlyst 70 which has high activity and selectivity at temperatures up to 190 °C. Two process options are proposed for a plant capacity of 26.5 ktpy: a reaction-separation-recycle (R-S-R) system based on an adiabatic tubular reactor and a catalytic distillation process. Both processes were optimized in terms of total annual costs (481 and 523 k$/year), leading to specific energy requirements of 225 and 256 kWh/ton DNPE, respectively. The controllability was assessed by dynamic simulation performed in Aspen Dynamics.

Conclusion

Compared with the membrane reactor reported earlier, the new DNPE process alternatives (i.e. conventional reaction-separation-recycle system and catalytic distillation) are better process candidates, requiring simpler units leading to much smaller investment costs, while also having good controllability.

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Background
Di-n-pentyl ether (DNPE) is a good candidate for diesel fuel formulations due to its blending cetane number, good cold flow properties and effectiveness in reducing diesel exhaust emissions, particulates and smokes. However, novel processes are required in order to drive the production costs down and to increase the efficiency at industrial scale.
Results
The dehydration of 1-pentanol to yield DNPE is catalyzed by thermally stable resins, such as Amberlyst 70 which has high activity and selectivity at temperatures up to 190 °C. Two process options are proposed for a plant capacity of 26.5 ktpy: a reaction-separation-recycle (R-S-R) system based on an adiabatic tubular reactor and a catalytic distillation process. Both processes were optimized in terms of total annual costs (481 and 523 k$/year), leading to specific energy requirements of 225 and 256 kWh/ton DNPE, respectively. The controllability was assessed by dynamic simulation performed in Aspen Dynamics.
Conclusion
Compared with the membrane reactor reported earlier, the new DNPE process alternatives (i.e. conventional reaction-separation-recycle system and catalytic distillation) are better process candidates, requiring simpler units leading to much smaller investment costs, while also having good controllability.
Two stage anaerobic digestion for reduced hydrogen sulphide productionhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4682Two stage anaerobic digestion for reduced hydrogen sulphide productionJan Moestedt, Erik Nordell, Sara Hallin, Anna Schnürer2015-03-16T02:22:29.029109-05:00doi:10.1002/jctb.4682John Wiley & Sons, Inc.10.1002/jctb.4682http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4682Research Articlen/an/aAbstract

BACKGROUND

This study evaluated a two-stage process as an alternative to single-stage anaerobic degradation, with the aim of separating sulphidogenesis and methanogenesis while treating a mixture of organic fraction municipal solid waste (OFMSW) and thin stillage. For full-scale applications, no pH regulation was applied. The hydrolytic/acidogenic stage was evaluated with a hydraulic retention time (HRT) between 3–15 days, with and without recirculation of methanogenic stage reactor material.

RESULTS

Homoacetogenesis dominated in the hydrolytic/acidogenic stage. However, sulphate reduction was unsuccessful. Using a two-stage approach with OFMSW at a HRT of 10 days in the first stage and 28 days in the second stage resulted in a 12% increase in specific methane production and a 6% increase in methane content. The two-stage process with thin stillage was less effective, probably because of decreasing pH (<4) in the first stage.

CONCLUSION

Two-stage operation resulted in too low pH (~4) for successful sulphate reduction in the first stage. However the resulting pH and applied organic loading rate caused homoacetogenesis to dominate producing acetate as a favourable energy carrier between the stages.

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BACKGROUND
This study evaluated a two-stage process as an alternative to single-stage anaerobic degradation, with the aim of separating sulphidogenesis and methanogenesis while treating a mixture of organic fraction municipal solid waste (OFMSW) and thin stillage. For full-scale applications, no pH regulation was applied. The hydrolytic/acidogenic stage was evaluated with a hydraulic retention time (HRT) between 3–15 days, with and without recirculation of methanogenic stage reactor material.
RESULTS
Homoacetogenesis dominated in the hydrolytic/acidogenic stage. However, sulphate reduction was unsuccessful. Using a two-stage approach with OFMSW at a HRT of 10 days in the first stage and 28 days in the second stage resulted in a 12% increase in specific methane production and a 6% increase in methane content. The two-stage process with thin stillage was less effective, probably because of decreasing pH (<4) in the first stage.
CONCLUSION
Two-stage operation resulted in too low pH (~4) for successful sulphate reduction in the first stage. However the resulting pH and applied organic loading rate caused homoacetogenesis to dominate producing acetate as a favourable energy carrier between the stages.
Molecular Imprinting in Hydrogels using Reversible Addition-Fragmentation Chain Transfer Polymerization and Continuous Flow Micro-Reactorhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4681Molecular Imprinting in Hydrogels using Reversible Addition-Fragmentation Chain Transfer Polymerization and Continuous Flow Micro-ReactorP. Kadhirvel, C. Machado, A. Freitas, T. Oliveira, R.C.S. Dias, M.R.P.F.N. Costa2015-03-13T02:27:56.822236-05:00doi:10.1002/jctb.4681John Wiley & Sons, Inc.10.1002/jctb.4681http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4681Research Articlen/an/aAbstract

Results

The feasibility of operation with a continuous flow micro-reactor for particles production was demonstrated. A comparative evaluation was carried out between batch and micro-reactor produced imprinted and non-imprinted hydrogels. Experimental results proved that molecular imprints generated by free radical polymerization and controlled radical polymerization showed outstanding performance in the adsorption behavior: the q value estimated found to be about 6000 times higher than the value presented by other researchers. Solid phase extraction results further evidenced the promising imprinting with hydrogels using free radical polymerization and controlled radical polymerization by retaining ca. 100% of 3-aminopyridine. Imprinting factor of 4.3 presented in this research appears to be the best value shown so far.

Conclusion

The imprinted materials were successfully prepared both in batch and with a continuous flow micro-reactor. The inclusion of reversible addition-fragmentation chain transfer agent in controlled radical polymerization was congenial in optimizing the experimental conditions in the continuous microfluidic approach. Though the reversible addition-fragmentation chain transfer agent was very useful in controlling the reaction kinetics, imprinted micro-particles showed the existence of both non-specific and imprinted sites. It is worth the extension of this work demonstrating the impact of reversible addition-fragmentation chain transfer agents in molecular imprinting, considering also the operation in continuous flow micro-reactor to obtain tailored smart hydrogel particles.

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Background
Stimuli responsive imprinted hydrogel micro-particles were prepared using reversible addition-fragmentation chain transfer polymerization for targeting genotoxic impurity aminopyridine in aqueous environment using a continuous flow micro-reactor.
Results
The feasibility of operation with a continuous flow micro-reactor for particles production was demonstrated. A comparative evaluation was carried out between batch and micro-reactor produced imprinted and non-imprinted hydrogels. Experimental results proved that molecular imprints generated by free radical polymerization and controlled radical polymerization showed outstanding performance in the adsorption behavior: the q value estimated found to be about 6000 times higher than the value presented by other researchers. Solid phase extraction results further evidenced the promising imprinting with hydrogels using free radical polymerization and controlled radical polymerization by retaining ca. 100% of 3-aminopyridine. Imprinting factor of 4.3 presented in this research appears to be the best value shown so far.
Conclusion
The imprinted materials were successfully prepared both in batch and with a continuous flow micro-reactor. The inclusion of reversible addition-fragmentation chain transfer agent in controlled radical polymerization was congenial in optimizing the experimental conditions in the continuous microfluidic approach. Though the reversible addition-fragmentation chain transfer agent was very useful in controlling the reaction kinetics, imprinted micro-particles showed the existence of both non-specific and imprinted sites. It is worth the extension of this work demonstrating the impact of reversible addition-fragmentation chain transfer agents in molecular imprinting, considering also the operation in continuous flow micro-reactor to obtain tailored smart hydrogel particles.
Butyric acid production from recycled waste paper by immobilized Clostridium tyrobutyricum in a fibrous-bed bioreactorhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4680Butyric acid production from recycled waste paper by immobilized Clostridium tyrobutyricum in a fibrous-bed bioreactorJin Huang, Hongliang Dai, Ren Yan, Pu Wang2015-03-13T02:26:56.25554-05:00doi:10.1002/jctb.4680John Wiley & Sons, Inc.10.1002/jctb.4680http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4680Research Articlen/an/aAbstract

Background

Recycled waste paper (RWP) has been considered as a low-cost substrate for cost-effective production of various biofuels and chemicals. The aim of this work was to utilize the fermentable sugar obtained from RWP, and thus to develop an alternative source of butyric acid to replace the petroleum-based product.

Results

RWP hydrolysate was successfully utilized for enhanced production of butyric acid in a fibrous-bed bioreactor (FBB) with a high titer (53.42 g L−1) and high selectivity (43.43 g g−1 butyrate/acetate ratio) in fed-batch fermentation. A repeated-batch fermentation process was carried out in which highly consistent butyrate yield (0.41 g g−1 utilized sugar), titer (20.96 g L−1), and productivity (1.62 g L−1 h−1) were achieved, demonstrating a stable and reliable long-term performance. Glucose and xylose, two major fermentable sugars in RWP hydrolysate, could be simultaneously consumed for butyrate production, providing high substrate utilization efficiency. Moreover, it was confirmed the presence of metabolic pathway shift from acetate-forming pathway towards butyrate synthesis.

Conclusion

High concentration of fermentable sugar solutions could be obtained from recycled waste paper, and could be utilized successfully for butyric acid production. The results also showed that the developed process was cost-effective and benign for environmental protection.

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Background
Recycled waste paper (RWP) has been considered as a low-cost substrate for cost-effective production of various biofuels and chemicals. The aim of this work was to utilize the fermentable sugar obtained from RWP, and thus to develop an alternative source of butyric acid to replace the petroleum-based product.
Results
RWP hydrolysate was successfully utilized for enhanced production of butyric acid in a fibrous-bed bioreactor (FBB) with a high titer (53.42 g L−1) and high selectivity (43.43 g g−1 butyrate/acetate ratio) in fed-batch fermentation. A repeated-batch fermentation process was carried out in which highly consistent butyrate yield (0.41 g g−1 utilized sugar), titer (20.96 g L−1), and productivity (1.62 g L−1 h−1) were achieved, demonstrating a stable and reliable long-term performance. Glucose and xylose, two major fermentable sugars in RWP hydrolysate, could be simultaneously consumed for butyrate production, providing high substrate utilization efficiency. Moreover, it was confirmed the presence of metabolic pathway shift from acetate-forming pathway towards butyrate synthesis.
Conclusion
High concentration of fermentable sugar solutions could be obtained from recycled waste paper, and could be utilized successfully for butyric acid production. The results also showed that the developed process was cost-effective and benign for environmental protection.
High conversion efficiency of Japanese cedar hydrolyzates into acetic acid by co-culture of Clostridium thermoaceticum and Clostridium thermocellumhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4679High conversion efficiency of Japanese cedar hydrolyzates into acetic acid by co-culture of Clostridium thermoaceticum and Clostridium thermocellumHarifara Rabemanolontsoa, Yoshimizu Kuninori, Shiro Saka2015-03-12T03:39:40.292456-05:00doi:10.1002/jctb.4679John Wiley & Sons, Inc.10.1002/jctb.4679http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4679Research Articlen/an/aAbstract

BACKGROUND

Acetic acid is an important reagent and a precursor in chemical and material industries. It is largely manufactured from fossil resources, but with increasing environmental concerns and uncertain petroleum availability, producing organic acids from renewable biomass became a priority. Several researchers have demonstrated acetic acid production from model compounds, food products or a minor portion of lignocellulosic biomass but the simultaneous fermentation of all biomass-derived products has not been reported yet. This work demonstrates the unique capabilities of Clostridium thermoaceticum and Clostridium thermocellum in co-culture to convert most products obtained from hot-compressed water treatment of Japanese cedar into acetic acid.

RESULTS

Under an optimal pH found to be 6.5, most of cello-oligosaccharides and xylo-oligosaccharides as well as the majority of monosaccharides were completely consumed after 40 h, while the lignin-derived products, organic acids, decomposed and dehydrated compounds required 72 h to be fermented. Overall, it was found that most of the water-soluble lignocellulosic hydrolyzates were successfully transformed into acetic acid, leading to high carbon conversion efficiency of 84.9 %.

CONCLUSION

Biomass-derived compounds from hot-compressed water treatment were efficiently converted to acetic acid, a valuable intermediate for further biotechnological production of chemicals and materials to substitute fossil-derived ones.

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BACKGROUND
Acetic acid is an important reagent and a precursor in chemical and material industries. It is largely manufactured from fossil resources, but with increasing environmental concerns and uncertain petroleum availability, producing organic acids from renewable biomass became a priority. Several researchers have demonstrated acetic acid production from model compounds, food products or a minor portion of lignocellulosic biomass but the simultaneous fermentation of all biomass-derived products has not been reported yet. This work demonstrates the unique capabilities of Clostridium thermoaceticum and Clostridium thermocellum in co-culture to convert most products obtained from hot-compressed water treatment of Japanese cedar into acetic acid.
RESULTS
Under an optimal pH found to be 6.5, most of cello-oligosaccharides and xylo-oligosaccharides as well as the majority of monosaccharides were completely consumed after 40 h, while the lignin-derived products, organic acids, decomposed and dehydrated compounds required 72 h to be fermented. Overall, it was found that most of the water-soluble lignocellulosic hydrolyzates were successfully transformed into acetic acid, leading to high carbon conversion efficiency of 84.9 %.
CONCLUSION
Biomass-derived compounds from hot-compressed water treatment were efficiently converted to acetic acid, a valuable intermediate for further biotechnological production of chemicals and materials to substitute fossil-derived ones.
A Thermo-Alkaline Lipase from a New Thermophile Geobacillus thermodenitrificans AV-5 with Potential Application in Biodiesel Productionhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4678A Thermo-Alkaline Lipase from a New Thermophile Geobacillus thermodenitrificans AV-5 with Potential Application in Biodiesel ProductionLew P. Christopher, Vasudeo P. Zambare, Archana Zambare, Hemanathan Kumar, Ladislav Malek2015-03-11T10:31:13.784362-05:00doi:10.1002/jctb.4678John Wiley & Sons, Inc.10.1002/jctb.4678http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4678Research Articlen/an/aAbstract

BACKGROUND

A thermophilic lipase-producing Geobacillus thermodenitrificans strain AV-5 was isolated from the Mushroom Spring of Yellowstone National Park in WY, USA and studied as a source of lipase for transesterification of vegetable oils to biodiesel.

RESULTS

A maximum activity of 330 U/ml was produced on 2% (v/v) waste cooking oil at 50 °C, pH 8, aeration rate of 1 vvm and agitation speed of 400 rpm. However, the higher lipase productivity (14.04 U/ml/h) was found maximum at volumetric oxygen transfer coefficients (kLa) value of 18.48/h. The partially purified lipase had a molecular weight, temperature and pH optimum of 50 kDa, 65 °C and pH 9, respectively, and was thermo-alkali stable: at 70 °C, it retained 81% activity and 45% stability; at pH 10, it lost only 15% and 2.6% of its maximum activity and stability, respectively. Enzyme kinetic studies with p-nitrophenyl laurate as substrate revealed high substrate specificity (km of 0.440 mM) and kinetic activity (vmax of 556 nmol/ml/min) of lipase.

CONCLUSIONS

The kLa was found to be highly dependent on aeration and agitation rates. Following optimization of fermentation medium and parameters, a 7.5-fold increase in lipase production by G. thermodenitrificans was attained. The lipase activity and substrate specificity (as km) are among the highest reported in literature for bacterial lipases. It was demonstrated that the enzyme can produce biodiesel from waste cooking oil with a conversion yields of 76%.

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BACKGROUND
A thermophilic lipase-producing Geobacillus thermodenitrificans strain AV-5 was isolated from the Mushroom Spring of Yellowstone National Park in WY, USA and studied as a source of lipase for transesterification of vegetable oils to biodiesel.
RESULTS
A maximum activity of 330 U/ml was produced on 2% (v/v) waste cooking oil at 50 °C, pH 8, aeration rate of 1 vvm and agitation speed of 400 rpm. However, the higher lipase productivity (14.04 U/ml/h) was found maximum at volumetric oxygen transfer coefficients (kLa) value of 18.48/h. The partially purified lipase had a molecular weight, temperature and pH optimum of 50 kDa, 65 °C and pH 9, respectively, and was thermo-alkali stable: at 70 °C, it retained 81% activity and 45% stability; at pH 10, it lost only 15% and 2.6% of its maximum activity and stability, respectively. Enzyme kinetic studies with p-nitrophenyl laurate as substrate revealed high substrate specificity (km of 0.440 mM) and kinetic activity (vmax of 556 nmol/ml/min) of lipase.
CONCLUSIONS
The kLa was found to be highly dependent on aeration and agitation rates. Following optimization of fermentation medium and parameters, a 7.5-fold increase in lipase production by G. thermodenitrificans was attained. The lipase activity and substrate specificity (as km) are among the highest reported in literature for bacterial lipases. It was demonstrated that the enzyme can produce biodiesel from waste cooking oil with a conversion yields of 76%.
Se-catalyzed Process of Sodium Bisulfite Disproportionationhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4675Se-catalyzed Process of Sodium Bisulfite DisproportionationLiyuan Chai, Bentao Yang, Hui Liu, Kaisong Xiang, Shu Yang, Cong Peng2015-03-05T06:57:48.906905-05:00doi:10.1002/jctb.4675John Wiley & Sons, Inc.10.1002/jctb.4675http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4675Research Articlen/an/aAbstract

Background

SO2 is an important gaseous pollutant that seriously affects environment and human health. The most common method for SO2 removal is absorption by NaOH solution and then forming HSO3−. Since generation of high-valuable products and reduction of alkali consumption are important in views of economy and practical application, a selenium-catalyzed HSO3− disproportionation was developed in this study.

Results

Selenium decreased the reaction temperature of HSO3− disproportionation from > 433 K to 343 K. Effects of HSO3− concentration, temperature, selenium dosage, and stirring intensity were investigated. Selenium could be used 5 times at least with stable catalytic performance, indicating a satisfactory reusability. More importantly, the catalytic mechanism was proposed using dynamic light scattering, differential scanning calorimetric and UV-visible transmittance spectrophotometer. Results showed that selenium-catalyzed HSO3− disproportionation experienced a solid-liquid-solid phase transformation process. During this process, SeSO32− and HSe− were identified as the intermediates. Furthermore, products, i.e. sulfur and sodium bisulfate, were characterized to demonstrate their structure and composition.

Conclusion

Selenium was an efficient catalyst for HSO3− disproportionation. This catalytic process offered the advantages of less consumption of alkali and production of high-valuable products, and thus was a potential alternative to other technology for SO2 removal in practical application.

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Background
SO2 is an important gaseous pollutant that seriously affects environment and human health. The most common method for SO2 removal is absorption by NaOH solution and then forming HSO3−. Since generation of high-valuable products and reduction of alkali consumption are important in views of economy and practical application, a selenium-catalyzed HSO3− disproportionation was developed in this study.
Results
Selenium decreased the reaction temperature of HSO3− disproportionation from > 433 K to 343 K. Effects of HSO3− concentration, temperature, selenium dosage, and stirring intensity were investigated. Selenium could be used 5 times at least with stable catalytic performance, indicating a satisfactory reusability. More importantly, the catalytic mechanism was proposed using dynamic light scattering, differential scanning calorimetric and UV-visible transmittance spectrophotometer. Results showed that selenium-catalyzed HSO3− disproportionation experienced a solid-liquid-solid phase transformation process. During this process, SeSO32− and HSe− were identified as the intermediates. Furthermore, products, i.e. sulfur and sodium bisulfate, were characterized to demonstrate their structure and composition.
Conclusion
Selenium was an efficient catalyst for HSO3− disproportionation. This catalytic process offered the advantages of less consumption of alkali and production of high-valuable products, and thus was a potential alternative to other technology for SO2 removal in practical application.
Numerical simulation of NO2 absorption using sodium sulfite in a spray towerhttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4669Numerical simulation of NO2 absorption using sodium sulfite in a spray towerZhuokai Zhuang, Chenglang Sun, Nan Zhao, Haiqiang Wang, Zhongbiao Wu2015-02-13T03:41:18.227237-05:00doi:10.1002/jctb.4669John Wiley & Sons, Inc.10.1002/jctb.4669http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4669Research Articlen/an/aAbstract

Background

Wet flue gas desulfurization combined with ozone is a promising technology which could remove NOx effectively. However, there are few reports focusing on the simulations regarding the absorption process of NO2 in a spray tower. A Computational Fluid Dynamics model including the chemical absorption was developed to simulate the absorption process of NO2. Simulations of different cases were executed to explore the influences of operating conditions.

Results

The errors between the predicted and experimental values were less than 5 % under different operating conditions and the model had depicted the tendency very well. For instance, an increase in L/G from 11 to 16 resulted in a growth of η from 90.9 % to 96.3 %. When the solution concentration raised from 0.025 mol/L to 0.0875 mol/L could result in an increase of η from 89.1 % to 98.6 %.

Conclusion

The developed model in present work was effective in determining the operating parameters of the spray tower for NO2 absorption, which could be utilized for the design and optimization of industrial apparatus. Moreover, the model can also evaluate the best positions of the spraying nozzles, the distance between the spray levels and other parameters for industrial application.

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Background
Wet flue gas desulfurization combined with ozone is a promising technology which could remove NOx effectively. However, there are few reports focusing on the simulations regarding the absorption process of NO2 in a spray tower. A Computational Fluid Dynamics model including the chemical absorption was developed to simulate the absorption process of NO2. Simulations of different cases were executed to explore the influences of operating conditions.
Results
The errors between the predicted and experimental values were less than 5 % under different operating conditions and the model had depicted the tendency very well. For instance, an increase in L/G from 11 to 16 resulted in a growth of η from 90.9 % to 96.3 %. When the solution concentration raised from 0.025 mol/L to 0.0875 mol/L could result in an increase of η from 89.1 % to 98.6 %.
Conclusion
The developed model in present work was effective in determining the operating parameters of the spray tower for NO2 absorption, which could be utilized for the design and optimization of industrial apparatus. Moreover, the model can also evaluate the best positions of the spraying nozzles, the distance between the spray levels and other parameters for industrial application.
Transformation of tetramethyldisiloxane in used oil alkali treatment conditions: mechanism and kinetic modelinghttp://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4673Transformation of tetramethyldisiloxane in used oil alkali treatment conditions: mechanism and kinetic modelingAntonina Kupareva, Johan Wärnå, Henrik Grénman, Dmitry Yu Murzin2015-03-31T09:20:34.460188-05:00doi:10.1002/jctb.4673John Wiley & Sons, Inc.10.1002/jctb.4673http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2Fjctb.4673Research Articlen/an/aAbstract

BACKGROUND

The behavior of silicon species in the recycling processes of waste lube oils is of great interest because of the negative effect of silicon compounds on the performance of hydrotreating catalysts and the formation of undesired solid deposits at various locations in the re-refining units. To operate alkali treatment of silicon-containing used oils efficiently in the recycling industry prediction of silicon species behavior is required. To this end kinetic modeling of the base catalyzed transformation of a model siloxane compound was done.

RESULTS

A kinetic model was developed for tetramethyldisiloxane (TMDS) transformation reactions under industrially relevant alkali treatment conditions in dodecane with sodium hydroxide as alkali agent. A reaction scheme describing the main pathways of TMDS transformation was proposed considering experimental and literature data. The studied model compound underwent hydrolysis, condensation and disproportionation reactions with formation of different molecular weight linear siloxanes. The latter were transformed to cyclic siloxanes through sodium silanolates generation. The data obtained experimentally were validated with the advanced kinetic model.

BACKGROUND

Polymer dispersed liquid crystal (PDLC) films have a range of applications varying from switchable windows to new optical memory devices. They switch from an opaque state, when liquid crystal molecules are randomly dispersed, to a transparent state, when liquid crystal molecules are aligned, simply by applying a small voltage. On some PDLC films, the transparent state is retained even when the voltage is switched off; this is called permanent memory effect (PME). This process is totally reversible, returning to the initial opaque state either through heating or applying a higher frequency electric field when using a two frequency liquid crystal.

RESULTS

In this work, the impact on the electro-optical response of PDLC films as a result of adding an additive was studied. This performance is affected by several factors, the most important being the anchorage force. This anchorage force is modified with the addition of an additive such as TX-100. As a result, it was verified that the addition of TX-100, increased the PME up to 98.7% and decreased the voltage required to achieve 90% of maximum transmittance to 2 V µm−1.

RESULTS

Trickling liquid velocity and co-current flow were selected as the most appropriate manipulated variable and flow pattern configuration compared with manipulating the air supply flow rate and a counter-current flow pattern in order to improve gas–liquid oxygen mass transfer in abiotic conditions. The influence of trickling liquid velocity on the performance of a lab-scale biotrickling filter treating high loads of H2S in a biogas mimic and operating in co-current flow at neutral pH and packed with plastic pall rings was investigated.

BACKGROUND

Industrial odor removers are two-phase flow systems that use effective microorganisms to capture malodor-producing gases from the surroundings. The potency of such systems depends on the interaction of gas with the microorganisms. Therefore, the flow and mass transport properties are key to defining the phenomenon more clearly.

RESULTS

An efficient mechanism for mixing the two-phase flow is required to enhance the interaction between the gas and microorganisms. Gas flow must also be controlled to obtain a large residence time in the water basin and facilitate the microorganisms to maximize the usage of malodor-producing gases. One method of improving the gas residence time is by installing baffles in the water basin. However, the installation of baffles also limits the gas concentration distribution in the water basin. Placing a rotating drum in addition to the baffles may overcome the limitations on gas distribution in the water basin. Gas volume fractions, interfacial area per volume, and gas concentration are evaluated to observe the mixing and gas dissolution phenomenon.

BACKGROUND

This work presents a novel approach to the understanding of electrostatic phenomena and sorbate–sorbent interactions in oil sorption. The study focuses on sorption of sunflower oil onto regranulated cork granules as promising natural sorbents.

RESULTS

It was shown that lowering the pH caused neutralization of negative surface charge by the positive hydrogen ions, leading to a reduction in the negative value of ζ-potential, and further destabilization of the emulsion, and an increase in oil and grease (O&G) uptake by cork granules. The effect of ionic strength was studied using a 3-level, 2-factor (32) full factorial design with O&G removal efficiency as the response variable. Linear effects of NaCl concentration, pH, and their interaction were found to be statistically significant (P < 0.05). Higher salt concentrations enhanced O&G removal due to double layer compression. Kinetic and equilibrium studies showed that the sorption process could be well described by a mechanism of partitioning governed by the external film fluid resistance.

BACKGROUND

The bacterium Escherichia coli is a commonly used host for the production of recombinant protein biopharmaceutical products. One class of such molecules is antibody fragments, typified by the Crohn's disease and rheumatoid arthritis therapy Certolizumab pegol (Cimzia®). Antibody fragments generated in E. coli are often directed to the periplasm, so that disulphide bonding can occur and release can be simplified. However, many recombinant protein products are prone to misfolding and mislocalization. Here, we optimized the production of a Fab fragment, D1.3, and its release from the periplasm of E. coli using osmotic shock.

RESULTS

By minimizing stress imposed on the bacterial hosts and monitoring Fab, total protein and DNA concentrations of fractions isolated following osmotic release, we successfully targeted the majority of recombinant Fab to the periplasm and were able to rapidly define optimal harvest points. Coupled optimization of fermentation and release increased the Fab concentration of the periplasmic extract by more than 20-fold.

BACKGROUND

Despite the small concentration of emerging contaminants (ECs) in water systems, in recent years numerous works have reported potential toxicological risks associated with their presence in the environment, and recommending their elimination by different procedures, such as chemical oxidation processes.

RESULTS

The elimination of three selected ECs, amitriptyline hydrochloride, methyl salicylate and 2-phenoxyethanol in aqueous solutions by photochemically activated persulfate has been investigated. The main operating conditions, such as persulfate dose, temperature, pH and buffer used, were varied and efficiencies of elimination and apparent pseudo-first-order rate constants of the oxidation reactions were determined for comparison purposes. The role of reactive oxygen species generated in the system, such as SO4·− and HO·, in the overall oxidation of the ECs was determined by using suitable scavenger compounds. Moreover, thermally activated persulfate was around 15–50 times less reactive than the UV/persulfate system. Finally, second-order rate constants for the reaction between sulfate radical and each EC were determined by competition kinetics, and the values obtained were (4.8 ± 0.6) × 109 M−1 s−1 for amitriptyline hydrochloride, (9.2 ± 0.9) × 108 M−1 s−1 for methyl salicylate, and (1.38 ± 0.02) × 109 M−1 s−1 for 2-phenoxyethanol.

BACKGROUND

An ozonation catalyst needs to be recycled easily and to exhibit high activity in view of its practical application in wastewater treatment. In this study, magnetic mesoporous MgFe2O4 was successfully prepared and used as a new ozonation catalyst for degradation of Acid Orange II (AOII). The role of Mg in MgFe2O4 was revealed to explain the high activity by catalytic experiments and XPS analysis.

RESULTS

The degradation efficiency of AOII in the MgFe2O4/O3 process exceeds 90% over a wide pH range of 4.6–9.6, slightly affected by the solution pH. The catalytic activity of MgFe2O4 is much higher than that of MgO, Fe2O3 and also their mixture (MgO+Fe2O3) with identical molar ratio of Mg2+ to Fe3+, indicating the first role of Mg, i.e. coupling with Fe to present a synergistically catalytic effect. Furthermore, MgFe2O4 possesses a reaction rate constant at least 2.3 times that of NiFe2O4, MnFe2O4, and CuFe2O4. It illustrates the second role of Mg, i.e. causing the high electron density on lattice oxygen in MgFe2O4 indicated by XPS and thus favoring activation of the electrophilic ozone.

Background

Dehydration of biomass-based fermentation product is an essential process in the production of biofuels ethanol for industrial applications. Cassava starch, an adsorbent with high efficiency, can be fermented after saturating with water, which overcomes the shortcomings of high energy consumption bioethanol production. Therefore, the aim of the present study was to prepare cassava starch-based adsorbents with high adsorption efficiency that do not affect fermentative production.

Results

Porous cassava starch granules, which can be fermented to produce biofuel ethanol, were formed through the partial hydrolysis of starch using amylase and ultrasonication. The structural changes in cassava starch granules were also studied to prove that porous starch could be reused as feedstock for biomass-based fuel ethanol production after adsorption. Finally, an adsorption experiment proved that the modified cassava adsorbents had better absorptive properties than the native cassava.

BACKGROUND

The efficiency of H2 production by dark fermentation described in the literature is around 50% of the maximum theoretical value and the experiments are mostly carried out over short-term operations. This present study evaluated H2 production in a UASB (upflow anaerobic sludge blanket) reactor operated at 55 °C for 366 days using a synthetic substrate based on sucrose. The reactor response to an increased organic loading rate (OLR) was assessed by applying three different hydraulic retention times (HRTs): 12 h (211 days), 6 h (71 days), and 2 h (84 days).

RESULTS

CH4 was observed in the biogas during startup. The highest average values of the molar H2 flow rate (MHFR), volumetric H2 production rate (VHPR), and H2 yield (HY) were achieved at a HRT of 2 h, and were, respectively, 14.00 ± 5.24 mmol h−1, 75.33 ± 24.65 mL H2 L−1.h−1, and 1.73 ± 1.14 mol–H2 mol-suc−1. Considering only the unstable steady-state period, HY average at a HRT of 2 h was 2.56 ± 0.84 mol–H2 mol-suc−1.

BACKGROUND

Currently, several techniques exist for the downstream processing of protein, phytic acid and sinapic acid from rapeseed and rapeseed meal, but no technique has been developed to separate all of the components in one process. In this work, two new downstream processing strategies focusing on recovering sinapic acid, phytic acid and protein from rapeseed meal were established.

RESULTS

The sinapic acid content was enhanced by a factor of 4.5 with one method and 5.1 with the other. The isolation of sinapic acid was accomplished using a zeolite-based adsorbent with high adsorptive and optimal desorption characteristics. Phytic acid was isolated using the anion-exchange resin Purolite A200®. In addition, the processes resulted in two separated protein fractions. The ratios of globulin and albumin ratio to the total protein were 59.2% and 40.1%, respectively. The steps were then combined in two different ways: (a) a ‘sequential process’ using the zeolite and A200 in batch processes; and (b) a ‘parallel process’ using only A200 in a chromatographic system to separate all of the compounds.

BACKGROUND

The aim of this work was the investigation of background water matrix impact on the effectiveness of a hybrid process, combining ceramic membrane microfiltration with oxidation processes for the treatment of surface water. The implementation of ozone-based oxidation during membrane filtration is expected to improve the overall process effectiveness, to enhance the permeate quality and to mitigate membrane fouling.

RESULTS

The novel hybrid reactor consisted of a submerged ceramic membrane, while the gas-containing ozone was introduced with the aid of ceramic gas spargers, producing fine bubbles. Total consumption of ozone during the experiments was achieved. Single ozonation experiments and ozonation in the presence of hydrogen peroxide were performed, as well as single microfiltration (MF). The novelty of this study is connected with the specific investigation of the carbonates and background ions influence on the effectiveness of various membrane hybrid treatment processes; the fouling process and mechanism during the application of membrane filtration was also examined. The connection between permeate quality and the extent of membrane fouling was also discussed.

BACKGROUND

Electrolysis with an iron anode is a novel way to provide ferrous activators for chemical oxidation. The objective of this study is to evaluate the performance of peroxymonosulfate (PMS) for chlorophenol destruction when compared with H2O2 and persulfate (PS), and to see whether the electrolysis mode facilitates the buildup of conditions that favor the activation of PMS and removal of chlorophenols.

RESULTS

Ferrous species can effectively activate the PMS over a wide pH range. In comparison with H2O2 and PS, PMS is less sensitive to the solution's pH and possesses stronger oxidation capability at alkaline pHs. The optimal molar ratio of PMS to Fe(II) activator is 1:1 for the destruction of 2,4-dichlorophenol (2,4-DCP). The column experiments show that an acidic zone developed downstream from the anode is favorable to maintain ferrous ions and subsequent activation of PMS. The reactivity of the PMS can be manipulated by varying the electrical currents, and the process demonstrates effectiveness for treating organic contaminants. 2,4-DCP contaminated groundwater shows decreased biotoxicity after the chemical oxidation process without considering the residual PMS.

BACKGROUND

Cyanobacteriae and microalgae industries require large amounts of water for their cultivation. Reusing the Arthrospira platensis culture medium is scarcely evaluated in the literature. This work evaluates coagulation and adsorption as a simultaneous process to treat A. platensis spent medium by applying different concentrations of powdered activated carbon (PAC) and ferric sulfate (S) and by using different contact times (T) to remove organic matter and pigments.

BACKGROUND

Membranes are the core and the main limitation of pervaporation. For example, in certain cases (more often for organic–organic mixtures) a pure product is not attainable as a permeate of a single stage and a series of membrane stages spaced by a condenser is required, making the process economically unacceptable.

RESULTS

This work discusses the use of an alternative approach by exploring the multi-stage-batch-pervaporation (MSBP) unit operation. Here, the permeate obtained after each batch-stage is recycled to the feed tank to increase the permeate product purity in a following stage. The separation of methanol–methyl acetate mixtures was chosen as a case study.

Simulations demonstrate how a multi-stage-batch-pervaporation unit is able to meet product purity requirements, by varying the stage-termination condition and the number of stages, employing a single membrane-module and a single condenser.

Moreover, a new way to visualize pervaporation separation performance of different membranes is proposed to replace the pervaporation separation index (PSI) analysis.

BACKGROUND

Bioelectrochemical remediation of soils contaminated by petroleum hydrocarbons has received increasing attention as an effective approach to remove pollution with simultaneous electricity generation.

RESULTS

Here, glucose was added as a co-substrate in this system. The charge output of soil microbial fuel cells (MFCs) was enhanced by 262%, and the total petroleum hydrocarbon degradation rate increased by 200%. According to the increased dehydrogenase and polyphenol oxidase activities, the exogenetic glucose substantially activated hydrocarbon degradation bacteria (such as Alcanivorax). The Shannon–Wiener Index and richness of soil microbial community decreased after glucose addition, indicating that a selective enrichment of specific communities was imposed by glucose. Correlation analysis showed the biodiversity in soil far from the cathode was mainly determined by the concentration of petroleum hydrocarbons, while that in soil close to the cathode was dominated by the current.

BACKGROUND

The presence of high concentrations of fluoride in groundwater is a threat to the provision of potable water especially to rural communities. Various substances have been suggested for the removal of fluoride from water. This work investigates the characteristics of laterite, which makes it an adsorbent applicable to fluoride removal.

BACKGROUND

Microbial electrosynthesis represents a promising approach for renewable energy storage in which chemically stable compounds are produced using CO2 as feedstock. This report describes the continuous production of acetate through microbial electrosynthesis from CO2 and assesses how the production rates could be increased.

RESULTS

A continuous acetate production rate of 0.98 mmol C LNCC−1 d−1 was obtained using CO2 as feedstock and with pH control around 5.8. These conditions increased substrate availability and favoured microbial electrosynthesis. Cyclic voltammograms demonstrated the electroautotrophic activity on the biocathode surface, which increased with pH control and caused current demand and acetate production rate to rise exponentially.

BACKGROUND

Soils and sediments near military sites where training regularly occurs are vulnerable to contamination from toxic nitro explosives such as 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). In order to clean up the explosive-contaminated soils, several options have been investigated and evaluated as ex situ remediation processes, including alkaline hydrolysis, subcritical water degradation, zero-valent iron (Fe(0)) reduction, and Fe(0)-assisted Fenton oxidation. The kinetics of the remediation processes were evaluated and the toxicity of treated solutions determined using the Microtox® bioassay.

RESULTS

Kinetically, using four remediation methods, explosives were rapidly degraded in contaminated soils. Under optimal conditions, more than 99% of explosives were destroyed. However, the Microtox® bioassay showed that after degradation of explosives by alkaline hydrolysis, treated solutions did not show any decrease in toxicity, suggesting that hydrolytic products may still be toxic. Similarly, the Fe(0) reduction process did not significantly aid removal of toxicity due to the toxicity of reduction products. In contrast, subcritical water degradation and Fe(0)-assisted Fenton oxidation markedly reduced the toxicity of explosives. When a toxic metal (e.g. Pb in shooting ranges) co-existed with explosives, toxicity still remained after complete degradation of the explosives by subcritical water degradation or Fe(0)-assisted Fenton oxidation, indicating that additional treatment may be needed.

BACKGROUND

Functionalized activated carbon (FAC) was prepared by immobilizing the activated carbon (AC) synthesized from Acacia fumosa seeds in cacium-alginate beads. Synthesized FAC has been blended with polyphenylsulfone (PPSU) in the composition of 0.25 to 1 wt% with an increment of 0.25 wt% to prepare composite membranes of PPSU/FAC by wet phase inversion method. The existence of FAC in PPSU was confirmed by Fourier transform infra-red spectroscopy (FTIR) studies by the presence of characteristic functional groups of FAC. The influence of FAC on adsorption enhanced rejection of phenol during membrane filtration has been investigated.

RESULTS

The hydrophilicity of PPSU/FAC composite membranes has been improved by FAC as there was a profound reduction in contact angle from 71.8° to 43.8°. With the minimum loading of 0.25 wt% of FAC in PPSU, the maximum adsorption of phenol has taken place suggesting that the better dispersion of minimal loading will offer higher accessibility to adsorptive sites.

BACKGROUND

Mathematical models are very important tools for the development of proton exchange membrane (PEM) fuel cells. In this work, a one-dimensional, steady-state and two-phase flow model of a PEM fuel cell is presented.

RESULTS

The present two-phase flow model is able to predict the experimental results more accurately than its single-phase counterpart, especially for high current values. In addition, the model presented here also allows calculation of the threshold current density defining the boundary between single and two-phase regimes, which can be used to provide a set of operating conditions avoiding a high content of liquid water and the resulting negative effects on cell performance.

BACKGROUND

Remediation of oil spillage accidents requires efficient and low cost floating absorbents to remove small amounts of contaminant oil. In this work, a highly hydrophobic floating magnetic macroporous structure based on silica encapsulated Fe nanoparticles was prepared and used for oil absorption from water.

RESULTS

The magnetic macroporous materials were prepared by silica encapsulation of iron oxide/hydroxide nanoparticles followed by a thermal treatment with H2. Mössbauer, XRD, SEM/TEM, CHN, IR, TG/DTA and contact angle analyses showed that the Fe oxides nanoparticles are reduced by H2 to form Feo cores protected by silica which sinters to form a macroporous network. The surface reaction with octadecyltrimethoxysilane (Si(CH3O)3C18H37) was used to produce highly hydrophobic materials.

BACKGROUND

The utilization of biomass and agricultural wastes for production of biofuels is of interest as a research topic, since it could provide a cheaper process due to the wide availability and low cost of raw materials.

RESULTS

In this work the vapor phase hydrogenation of levulinic acid to γ-valerolactone over copper catalysts supported on ZrO2 was investigated. The catalysts were prepared by a wet impregnation method with Cu loadings varying from 2 to 20 wt% and characterized by various physico-chemical techniques. It was observed that copper dispersion and particle size obtained using a N2O decomposition method are in agreement with the findings derived from XRD and TPR. The catalytic functionalities are discussed in relation to the dispersion of copper and other structural properties of Cu species supported on ZrO2. A comparison of catalytic results of Cu/ZrO2 was made with CuO supported on Al2O3, SiO2 and TiO2.

BACKGROUND

Microwave-assisted hydrodistillation (MAHD) has widely been used to isolate essential oil from various plant materials, but it has not been applied yet to extract essential oil from juniper berries. The main goals of the present work were to establish a model describing the extraction kinetics and the chemical composition of the essential oil obtained.

RESULTS

A lower final essential oil yield from juniper berries was obtained by MAHD than by conventional hydrodistillation (HD). No significant differences in chemical compositions of the essential oils extracted by the two techniques were observed. The mechanism of both processes was the same and included fast (washing) and slow (diffusion) distillation of essential oil that occurred simultaneously.

BACKGROUND

Phosphorylated proteins have attracted widespread attention due to their crucial roles in regulating biological processes. Therefore, development of effective methods for identification and detection of phosphorylated proteins is an indispensable step to understand the roles of protein phosphorylation. The aim of this work is to prepare Ti4+-decorated polydopamine-grafted hybrid magnetic particles (Ti4+-PDA@Fe3O4) for highly efficient and selective separation of phosphorylated proteins.

RESULTS

Ti4+-PDA@Fe3O4 particles were synthesized and characterized. A wealth of hydroxyl groups in PDA enhanced the binding capacity of PDA@Fe3O4 for titanium ions. The selectivity of the particles for phosphorylated proteins relies on the affinity of phosphate groups in phosphorylated proteins to titanium ions on the surface of Ti4+-PDA@Fe3O4. The adsorption capacity of Ti4+-PDA@Fe3O4 for β-casein was 1273.9 mg g-1. The adsorption conditions and selectivity of Ti4+-PDA@Fe3O4 for phosphorylated proteins were studied. The feasibility of Ti4+-PDA@Fe3O4 for separation of phosphorylated proteins from milk was also investigated.

BACKGROUND

Microbial enhanced oil recovery is a potential technology to enhance crude oil recovery from depleted oil reservoirs and solve stagnant petroleum production. Relevant studies have mainly focused on the use of bacteria, with less attention paid to the potential of fungi. In this study, the efficiency of fungal extracellular enzymes for crude oil degradation and their feasibility for use in enhanced oil recovery were evaluated.

RESULTS

Six fungal cultures of Aspergillus spp. were isolated from oil-contaminated surface soil samples from an oilfield. The performance of fungal extracellular enzymes to degrade crude oil was investigated using solid enzyme preparations. All the enzyme preparations efficiently degraded the alkane, aromatic, resins, asphaltene, and decreased the viscosity of crude oil to varying degrees (max 59.0%). Enzymatic degradation of crude oil was accompanied by dynamic production of gases (CO2 and H2) and organic acids (oxalate and propionate). In addition, the enzyme preparations removed 83.40–87.78% of crude oil adsorbed on filter paper.

BACKGROUND

Ultrafiltration (UF) has led to the recovery of valuable products from seafood processing wastes. However, the use of crustacean process wastewaters as a source of bioactive compounds with application in the chemical, pharmaceutical and food industries has been scarcely studied to date.

RESULTS

This study reports the recovery of high concentrations of astaxanthin (10–13 µg mL−1) by 300 kDa ultrafiltration of shrimp cooking wastewater, indicating that astaxanthin is associated with high MW retained proteins. Individual UF with 300, 100 and 30 kDa MWCO membranes and the sequential UF 100 30 kDa were the most effective configurations for protein concentration. Hydrolysates from these three protein-concentrated fractions showed very potent ACE-inhibitory (1.98, 9.87 and 23.10 µg mL−1IC50 values) and ß-carotene bleaching activities compared with hydrolysates from other fish and seafood species.

BACKGROUND

Solid-state fermentation is a well-known bioprocess. The development of a solid-state fermentation reactor faces difficulties in controlling temperature gradients inside the bed. To understand this behavior, a good phenomenological model must be used. Furthermore, the model parameters must be obtained by a reliable and robust parameters estimation procedure, since often the model parameters are not available in the literature.

RESULTS

The heuristic particle swarm optimization (PSO) method was used to estimate the parameters of the reparametrized model through the minimization of a nonlinear-square objective function, since it is less sensitive to initial guesses than derivative based methods. Statistical analyses were made to evaluate the parameter estimation quality. Also, simulations with the reparametrized model were performed. All the analyses have revealed the great accuracy of the proposed model, predicting with very small residuals (errors) several experimental data sets of a solid-state fermentation process.

BACKGROUND

Malolactic fermentation (MLF) is a critical step in modern winemaking and the co-inoculation of lactic acid bacteria with yeasts represents an emerging approach to improve the quality of wine. This study aims to evaluate the effect of inoculation timing on the chemical and sensory characteristics of two commercial Cabernet Franc wines: (i) a control wine in which MLF was inoculated after the completion of alcoholic fermentation (AF); and (ii) a co-inoculated wine where simultaneous alcoholic and malolactic fermentations occurred.

RESULTS

Besides the expected full conversion of malic acid into lactic acid, the MLF with co-inoculum of yeast/bacteria at initial AF allowed for reduced fermentation times, i.e. faster winemaking process. Although important changes in the chemical parameters of wines were found, especially color intensity and volatile compounds, there was a trend on the sensory evaluation of wines with a greater perception of red and ripe fruits in the case of co-inoculation wine, while the control wine was dominated by notes of spice and herbs. The results of GC/MS analysis showed the largest differences for the 3-hydroxy-2-butanone (acetoin, the reduced form of diacetyl) and isoamyl alcohol concentrations, the former was 3.2 times higher under co-inoculum conditions, whereas the latter showed the opposite behavior.

BACKGROUND

The aim of this work was the examination of molasses wastewater treatment by the combination of activated sludge with ozonation, for the effective removal of refractories. In addition to biological treatment, samples were subjected to: (a) ozonation prior to activated sludge; (b) ozonation coupled with addition of hydrogen peroxide prior to activated sludge; (c) post-ozonation of activated sludge effluents; and (d) ozonation applied to influents and effluents, as a pre- and post-treatment of the biological process.

RESULTS

The activated sludge treatment of the mixture resulted in a 48% reduction of COD, while the combination of ozone pretreatment followed by biological treatment resulted in 66.5% COD removal and the production of an effluent with 240 mg L−1 COD. Therefore, it was concluded that ozone pretreatment might contribute to the enhancement of the biodegradability of the influent. This assumption was further supported by the examination of molecular weight distribution of wastewater samples by size exclusion chromatography.

BACKGROUND

Gamma(γ)-aminobutyric acid (GABA) is produced through an α-decarboxylation reaction of L-monosodium glutamate (MSG) using glutamate decarboxylase (GAD). The pH rise caused by the reaction inactivates the enzyme catalyst, which is active only under acidic conditions, and consequently leads to low reaction conversions. Employment of conventional acids and buffers inevitably forms salts, which result in serious problems in separation and purification of GABA. It is essential to render GAD active even at neutral and alkaline pHs. In the present study, we first apply a cross-linked aggregation method in order to extend the active range of GAD toward alkaline pH.

RESULTS

GAD from Escherichia coli was prepared as cross-linked enzyme aggregate (CLEA) in which the enzyme was precipitated using ammonium sulfate (60% saturation) and then cross-linked with glutaraldehyde (2%) in sodium acetate buffer (0.2 mol L−1, pH 4.6). The cross-linked aggregation extended an active pH range of GAD from 5.5 up to 8.0; as a result, the reaction conversion of 1 mol L−1 MSG into GABA was improved from 13% to 22%. Moreover, the CLEA of GAD was easily recovered after the reaction and reused retaining >95% of its initial activity during the first four cycles and >60% activity at the 10th cycle.

BACKGROUND

Carbon materials are appealing adsorbents for postcombustion CO2 capture applications. In the present work, the adsorption of H2O, which is an abundant component in flue gases, and its influence on the adsorption of CO2 is evaluated using a microporous carbon.

RESULTS

The adsorption and desorption isotherms of H2O at 12.5, 25, 50, 70 and 85 °C were obtained for relative pressures between 0 and 0.95. The average isosteric heat of adsorption of H2O on PPC is 46 kJ mol−1. The equilibrium of adsorption and desorption of H2O on PPC can be reasonably well described by the DJD model over the entire temperature and pressure range evaluated. Breakthrough experiments carried out with synthetic flue gas showed that the adsorption of CO2 is not hindered by H2O at short adsorption times, relevant for the adsorption of CO2. Moreover, PPC can be fully regenerated recovering its full adsorption capacity after extended exposure to humid gas.

BACKGROUND

Polyimide (PI) solvent-resistant nanofiltration (SRNF) membranes were prepared by a two-step method. The polyamic acid (PAA) precursor was synthesized first, and then PAA membranes were obtained via a non-solvent induced phase separation method. Finally, the PAA membranes were transformed into PI membranes by the thermal imidization method. The effect of molecular weight of precursor on the structure and performance of PI membranes was investigated in detail. In addition, the influence of other processing parameters, such as evaporation time and immersion time in the coagulation bath, on the performance of PI membranes prepared from PAA with different molecular weights was also investigated.

RESULTS

The results showed that the structure of PI membrane varied with PAA molecular weight. The PI membranes prepared from low molecular weight PAA failed to form a defect-free membrane with enough strength, and resulted in high flux but low rejection. Accordingly, PI membranes processed from PAA with high molecular weight retain rejection higher than 90% of FCF with decreased flux. The results also indicated that the optimized molecular weight of PAA should be between 1.23 × 105 g mol−1 and 2.44 × 105 g mol−1 to prepare defect-free PI membrane for nanofiltration. The results also showed that the performance of the PI membranes can be controlled by adjusting the evaporation time, immersion time, and also the operating pressure.

BACKGROUND

Cleanup of oil spills is a worldwide task needed to avoid serious environmental pollution. Recently, polyurethane (PU) sponge has been used as an oil absorbent, however, its efficacy is limited by its hydrophilic property.

RESULTS

This work describes the modification of PU sponge with ZnO microrods and palmitic acid (PA). A coating of ZnO microrods made the surface of PU sponge rough, which improved the hydrophobicity and oil-adsorption capacity of the sponge. Further immersion in PA solution reduced the surface energy, which enabled the rough surface to be superhydrophobic (water contact angle (CA) > 150°). The contact angles of water and oil on the prepared ZnO and PA modified (ZnO-PA sponge) sponge were 168.9° and 0°, respectively. Adsorption capacities of ZnO-PA sponge varied between 33 and 44 g g−1 for different oil samples, which were higher than those of the non-modified PU sponge (21–23 g g−1). Adsorption equilibrium for the adsorption process of ZnO-PA sponge was achieved within tens of seconds. Additionally, the ZnO-PA sponge showed excellent selectivity for oil over water, and high reusability.

BACKGROUND

Kinetics of adsorption and desorption associated with diffusion mechanisms is of crucial importance to use zeolites as catalysts. In particular, diffusion of ionic liquids (IL) is of interest when using them as solvent for reactions or preparing composite IL–Zeolite. This work investigated the kinetics of adsorption/desorption of 1-buthyl-3-methylimidazolium bromide ([BMIM]+Br−) into mordenite (MOR), a channel-like zeolite.

RESULTS

The adsorbed IL is characterized and quantified using infrared spectroscopy (FTIR), thermogravimetrical analysis (TGA) and CHN elemental analysis. The results show rapid adsorption of c. 0.7 mol of [BMIM]+Br− per gram of MOR but most of it remains in the pores of the zeolite upon desorption because only 9% is desorbed. CHN and TGA also suggest that adsorption of [BMIM]+Br− into the ammonium form of MOR can follow an ionic exchange mechanism. Experimental results can be fitted to a pseudo-second-order kinetic equation.

BACKGROUND

In recent years, the application of electrochemical wastewater treatment processes has proven to be very efficient in the removal of recalcitrant organic compounds. However, the scale-up of the boron-doped diamond (BDD) anode system for industrial applications has not been sufficiently evaluated. This study assesses the effect of increasing the number of compartments in the same electrochemical module (DiaCell® 1001) on the treatment of synthetic wastewater with pesticide 2,4-D and chlorides. This commercial module can be considered to be a stack of cells, in which the number of single cells varies from 2–10 and the anode areas range from 140–700 cm−2.

RESULTS

The results of the study demonstrate that an increase in the number of cells and a decrease in the resulting current density at the same current intensity caused an increase in the removal and mineralisation rates. Complete mineralisation was attained in all configurations tested. The production of hazardous species, such as chlorates and perchlorates, are also affected by the number of stacked cells, which causes them to be positioned lower in the stack due to the large number of cells.

BACKGROUND

In this study, polyesters of glycerol, aconitic acid and cinnamic acid were synthesized and studied for their potential application as scaffolds in tissue engineering. Aconitic acid can be recovered from molasses, while glycerol and cinnamic acid can be recovered from pretreated sugarcane bagasse used for bio-ethanol production. Polyester synthesis was carried out at different molar ratios of reactants at a temperature of 120 °C for 5 h. Synthesized polyesters were characterized chemically and mechanically, and evaluated for their cytotoxicity and chemical stability towards human adipose derived mesenchymal pluripotent stem cells (hASC).

RESULTS

Several cytocompatibility tests such as mass loss over a period of time, alamar blue to analyze growth and viability of hASC on polyester scaffolds, picogreen for total DNA content synthesized, indicated that these polyesters hold promise as tissue engineering scaffolds. For skin tissue engineering, especially for wound repair, thin film polyester scaffolds laden with hASC were grown in stromal medium supplemented with basic fibroblast growth factor (bFGF). For all the scaffolds, the amount of collagen synthesized in bFGF supplemented medium was significantly higher than the scaffolds with hASC in control (stromal) medium (P<0.05)

BACKGROUND

Fenton and photo-Fenton processes were explored as photochemical pre-treatments to improve the biodegradability of wastewater containing atrazine, a commercial pesticide. The effects of H2O2, Fe3+ and irradiation level on the degradation processes were studied and the optimal conditions determined.

RESULTS

Fenton and photo-Fenton oxidation systems were able to remove 85 and 100% of atrazine, respectively, in a 120 min period. These processes produced a biocompatible solution, removing 100% of the initial biorecalcitrant compound; however, cyanuric acid remained in the effluent after the chemical oxidation treatment due to the stability of the N-heterocyclic ring of this acid. Nevertheless, it was found that the cyanuric acid remaining from the photo-oxidative process can be removed by means of an anaerobic treatment.

BACKGROUND

Recently much research has been focused on the production and refinery of biobased fuels. The production of biofuels derived from lignocellulosic biomass is recognized as a promising route to produce biobased fuels responsibly. Often, product streams (e.g. glucose) still contain small amounts of undesired components (e.g. furans such as HMF). This study focuses on the removal of furans produced during the fermentation. In earlier work, styrene based resins have been identified as promising materials for this separation. In this work the kinetic properties of the most promising resin: DowexTM OptiporeTM L493 are studied.

RESULTS

The diffusion coefficient of 5 mg L−1 HMF was ∼8 × 10−12 m2 s−1 in water and 3.0 × 10−12 m2 s−1 in a glucose solution. The reduced diffusion coefficient in the particle when glucose is present is caused by the higher viscosity of the glucose solution and it indicates that diffusion is controlled by surface and pore diffusion. The breakthrough curves of HMF on Optipore showed that the column is very efficient under conditions of interest.

RESULTS

The P(V) loading capacity of the sorbent at a pH simulating the expected conditions in treated wastewaters was 92 ± 3 mg P-PO4 g−1 in single component solutions. The sorption of P(V) is affected slightly by the common ions typically present in these effluents such as Cl−, SO42− and NO3−, and a reduction of only 5% was observed (89 ± 2 mg P-PO4 g−1) in multicomponent solutions. The sorbent can be regenerated (95 ± 3%) using 4% (w/w) sodium hydroxide solution.

RESULTS

A mutant, BER208, was obtained by ARTP and ALE used successively. When cultured in a 3 L stirred bioreactor, the specific growth rate of BER208 was increased 3.12-fold compared with AFP111. Also, it consumed 40 g L−1 glucose and produced 27.9 g L−1 succinic acid with a glucose utilization rate of 0.54 g L−1 h−1 and succinic acid productivity of 0.38 g L−1 h−1, which were 3.7-fold and 2.5-fold higher than those of the original strain. Further investigation showed that the activities of glucokinase and phosphoenolpyruvate carboxykinase (PCK) were increased 3.3-fold and 16-fold in the mutant compared with the original strain.

BACKGROUND

Synthetic musks are massively used in personal care and cosmetic products and they reach the environment mainly because they are not completely removed in wastewater treatment plants (WWTPs). In this work, an innovative and simple chemical scoring and ranking approach was developed as a screening tool to evaluate the overall impact of musks on the environment, identifying priority compounds. This system is idealised as an important tool for a subsequently feasible environmental risk assessment of musks that may represent the overall contamination on a regional scale.

RESULTS

Physicochemical and toxicological properties of 18 synthetic musks estimated by (Q)SAR were successfully used for the chemical scoring and combined with observed data to estimate the environmental impact posed by these compounds on four environmental compartments.

BACKGROUND

One of the main components of dairy wastewaters is cheese whey. Although different technologies have been used extensively in the past for cheese-whey treatment, constructed wetlands (CWs) applications are limited. Furthermore, the effect of crucial operational parameters (e.g. temperature, pollutant loading rate) have not been thoroughly studied. Having this in mind, two horizontal subsurface flow pilot-scale CW units (one planted and one unplanted) were used to treat secondary cheese whey, in order to examine the effect of different chemical oxygen demand (COD) influent concentrations (1200 to 7200 mg L−1), hydraulic residence times (8, 4, 2 and 1 day) and temperature (2.4 to 32.9 °C).

RESULTS

During a 2-year operating period both pilot-scale units successfully removed organic matter, with COD removal efficiencies recorded at 91% and 77.2% for the planted and the unplanted unit, respectively. Hydraulic residence time affected COD removal efficiency only when limited to 1 day. Temperature significantly affected COD removal only in the unplanted unit.

BACKGROUND

Anaerobic ammonium oxidation (anammox) is a promising process for nitrogen removal, but it cannot always be used successfully in the presence of inorganic matter. The feasibility of using the anammox process for treating wastewater that contains fluoride was examined in this study. The short-term inhibitory effect was tested at various fluoride concentrations and exposure times, and diverse pre-exposure strategies were performed in special serum bottles. Subsequently, the long-term effect of fluoride stress was continuously monitored and evaluated in an upflow anaerobic sludge blanket (UASB) reactor.

RESULTS

The 50% inhibitory concentration (IC50) of fluoride for anammox biomass was calculated to be 767 mg L−1 in batch tests with an initial total nitrogen (TN) level of 200 mg L−1. A remarkable inhibitory effect of fluoride emerged when the substrate was supplied at >420 mg L−1 TN. The diameter and settling velocity of the granules significantly increased with the addition of 250 mg L−1 fluoride.

BACKGROUND

Decomposition of amoxicillin (AMX) and ciprofloxacin (CIP) in aqueous suspensions by two forms of ferrate (VI) were investigated. The effect of the initial concentration of antibiotics, pH, and ferrate (VI) dosage were examined. Model calculations were made by the Density Functional Theory (DFT) method (RB3LYP) taking into account the environmental parameters. LanL2DZ and 6-311G++(d, p) were taken as basic functions for the calculations. This was followed by analysis of two redox decomposition mechanisms of the ferrate ion, with the O2 molecule formation and electron density distribution, and the reaction mechanism of superoxide particle formation, which participates in the AMX and CIP oxidation process.

RESULTS

Ferrate (VI) degraded CIP more effciently than AMX in both forms. Electrogenerated ferrate (VI) was more efficient than direct use of its solid form. The removal efficiencies of CIP and AMX by electrogenerated ferrate (VI) were 80.9% and 63.7%, respectively.

BACKGROUND

The effects of designed methanol and co-substrate feeding strategies on fed-batch recombinant human growth hormone (rhGH) production by Pichia pastoris hGH-Mut+ were investigated.

RESULTS

The highest cell concentration was obtained as 157 g L−1 with the exponential feeding strategy where methanol was fed at a pre-calculated feeding rate based on pre-determined µ0 = 0.03 h−1, and mannitol concentration was kept constant at 50 g L−1 for t=0–6 h. The highest rhGH concentration was obtained as 1.3 g L−1 at t=54 h with the methanol-stat feeding strategy, where no co-substrate was used and the methanol concentration was kept at 5 g L−1 in the medium during the production phase. Thereafter, in another methanol-stat feeding strategy with pulse-fed sorbitol, the highest rhGH concentration was obtained as 1.2 g L−1 at t=42 h.

BACKGROUND

Lead citrate is an attractive precursor for the preparation of ultrafine leady oxide from the paste in spent lead-acid batteries through a novel hydrometallurgical process, since the recovered lead oxide could be recycled for the production of new lead acid batteries.

RESULTS

Two different metal organic complexes were synthesized from lead sulfate from the paste of spent lead-acid batteries in a leaching solution at two different initial pH values. Single crystals of the two precursors were obtained by conditioning and filtering from the leached solutions, and used for single crystal XRD analysis. At an initial pH of 3.5, the chemical formula of Precursor-I is deduced to be Pb(C6H6O7)·H2O while at an initial pH of 5.2, the chemical formula of Precursor-II is Pb3(C6H5O7)2·3H2O.

BACKGROUND

Urine is an abundant waste product which requires energy intensive treatment processes in modern wastewater treatment plants. However urine can be utilised as fertiliser in the form of struvite. Microbial fuel cells (MFCs) are a promising technology for treating waste while producing electricity. Combining these two approaches, a 3-stage MFC/struvite extraction process system was developed and its feasibility tested in order to maximise urine utilisation in terms of electricity generation and struvite recovery.

RESULTS

In the first stage, while generating electrical energy, MFCs accelerated urea hydrolysis, which was beneficial for the struvite precipitation process in the following stage. After collecting struvite by adding magnesium into the initial effluent, the supernatant was used at the final stage for additional power and more efficient COD reduction. In total, 82% of PO43−-P and 20% of COD of undiluted human urine were removed by the 3-stage system. Also 14.32 W m−3 (absolute power: 358 µW) and 11.76 W m−3 (absolute power: 294 µW) of power was produced from the 1st and 3rd stages of the system, respectively, during operation.

BACKGROUND

Electro-Fenton technology has already demonstrated its ability to degrade organic pollutants. In this treatment hydroxyl radicals are formed due to the reaction of the iron catalyst along with in situ electrogenerated H2O2. However, one of the main limitations of this system is the iron released in the treated effluent. Therefore, retention of iron is required, and in this study, the use of a new cathode in which the iron is fixed on nickel foam is proposed as a solution to the electro-Fenton treatment in continuous processes.

RESULTS

The retention of iron was ensured by its fixation on nickel foam using chitosan, an eco-friendly polymer, as coating agent. Different chitosan coatings were tested to optimize the manufacturing process of the new cathode. It was concluded that the best electrode for the electro-Fenton treatment of different dyes (Poly R-478 and Lissamine Green B) was obtained using a half-coating electrode cover with iron–chitosan of medium molecular weight. Furthermore, its reusability was positively evaluated in successive cycles. Finally, a continuous treatment using a fluidized bed reactor was successfully performed for the treatment of dye Lissamine Green B.

BACKGROUND

This study focused on understanding the reaction kinetics for the hydrocracking process. Oleic acid, as the main component of most bio-oils, was selected as feedstock for the hydrocracking process. The hydrocracking of oleic acid was performed in a laboratory scale trickle-bed reactor in the presence of a Ni–Zeolite β catalyst and hydrogen for hydrogenation. The concentrations of oleic acid and the three main components of jet fuel range hydrocarbons produced, which are nonane, decane and dodecane (C9, C10 and C12), were measured with GC analysis.

RESULTS

According to the aforementioned component concentrations, the rate of reaction and the related Arrhenius equation parameters were estimated. The reaction kinetic calculations were subjected to hydrocracking reactor modeling to gain a better understanding of hydrocracking. The concentrations of C9, C10 and C12 were assumed to be a separate lump of the hydrocarbons produced, namely middle hydrocarbon (MC). The reactant and MC lump concentrations throughout the reactor were measured and compared with experimental data. The modeling and experimental results are in reasonable agreement in terms of MC lump production and oleic acid conversion. The oleic acid and MC concentration profiles and reactor wall temperature profiles along the reactor were examined in this research.

BACKGROUND

Cellulose as a renewable biomaterial has forced attention on the use of cellulose-hydrolyzing enzymes for industrial bioconversion of lignocellulosic materials to glucose. This paper reports immobilization of cross-linked cellulase aggregates (CLEA) on the amine-functionalized Fe3O4@silica core-shell magnetic nanoparticles (MNPs).

RESULTS

The optimum pH of the cellulase cocktail upon immobilization (cellulase CLEA–MNP) shifted a little to the acidic side whereas the optimum temperature did not change significantly. The behavior of CMCase activity in the cellulase CLEA–MNP at pH and temperature values higher than the optimum was significantly different compared with free cellulase. Cellulase CLEA–MNP retained about 45% of its maximum activity at pH values higher than 4.8, while free cellulase lost its activity sharply. Immobilized cellulase in contrast to the free form retained about 65% of its maximum activity at 80°C. Cellulase CLEA–MNP had improved thermal stability at 65°C. Operational stability of the immobilized cellulase was also noticeable. After a sharp decrease during two cycles of CMC hydrolysis, cellulase CLEA–MNP retained 30% of its initial activity through six cycles of reuse.

BACKGROUND

A number of pretreatments have been reported in the literature aiming to improve yields with increases in degree of digestibility of the cellulose-enriched fractions, in reducing the process time recalcitrance and costs of a variety of chemicals reagents and physical processes were used. Nevertheless, none of them was considered completely satisfactory.

RESULTS

Modifications and simplifications were made in pretreatments to increase gravimetric yields and to decrease the losses of mass. The highest gravimetric yields and the lowest loss of mass were obtained for cellulose-enriched fractions resulting from microwave pretreatments. Loss of mass during treatments with sulfuric acid were due to dehydration of sugars forming furan aldehydes. Cellulose-enriched fractions PT6 and PT7 are certainly more easily by commercial enzymes as indicated by loss of mass.

BACKGROUND

Brightness stability of bleached chemical pulps is often associated with the final bleaching stages that should provide the removal of chromogenic species responsible for brightness reversion without compromising the papermaking potential. Aiming at promoting higher brightness stability, a partially bleached Eucalyptus globulus pulp (DED) of c. 88% ISO brightness was involved in a study of a final enzymatic stage (X) alternative to conventional chlorine dioxide (D) and hydrogen peroxide (P) bleaching stages (DEDX vs. DEDD and DEDX vs. DEDP). X stage was also applied before and after the final P or D stages (DEDDX/DEDXD and DEDPX/DEDXP) to produce high brightness pulps (c. 91%).

RESULTS

X stage with xylanase Pulpzyme HC allowed an increase of c. 1.5% in pulp brightness while decreasing the brightness reversion and a concomitant pulp yield loss of only 0.5%. Significant chemical savings were obtained in the final D (70%) or P (45%) stages to achieve targeted final brightness of c. 91%. DEDXD or DEDXP sequences had advantage over DEDDX and DEDPX, respectively, in terms of brightness stability of fully bleached pulps.

BACKGROUND

Two types of bleaching earths used in the production of green diesel, namely, sepiolite and palygorskite, were characterized by various physico-chemical methods, such as nitrogen adsorption, Hg porosimetry, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, Fourier transfom infrared spectroscopy, pH of the clay slurry, thermogravimetrical analysis (TGA) and X-ray diffraction analysis. The characteristics of fresh, spent and extracted bleaching earths were compared in the current study.

RESULTS

The results showed that particle sizes of the extracted adsorbents have decreased. Furthermore, some leaching of elements was confirmed by elemental analysis. A decrease in specific surface area of the adsorbents was observed thus compromising the economical feasibility of the reuse of these clays. TGA results showed that the oil content in spent sepiolite and palygorskite, which could be extracted was 35% and 12%, respectively. Extraction efficiencies were affected by the specific surface area of the clay.

BACKGROUND

Microalgae biodiesel has attracted considerable attention, however, low lipid content has significantly restricted its development. Many research studies have demonstrated that nutrient deficiency is an important factor stimulating lipid accumulation in algal cells. This present study investigated the combined effects of nitrogen, phosphorus, and carbon on algal lipid accumulation by Chlorella vulgaris in mixotrophic culture.

RESULTS

Phosphorus at 0.2 g L−1 concentration inhibited Chlorella vulgaris growth but did not influence lipid accumulation. High concentration of NaNO3 (3.75 g L−1) inhibited both algal growth and lipid accumulation. Nitrogen sufficiency can stimulate lipid accumulation. Glucose limitation restricted both biomass production and lipid accumulation, resulting in lipid content decrease even under nitrogen sufficiency. CO2 was unable to satisfy the carbon demand for lipid accumulation when glucose was exhausted in mixotrophic culture. The initial C:N ratio of culture medium played an important role in algal lipid accumulation. Lipid content was maintained at 7.6–11.3% when the initial C:N of culture was less than 50, while it increased significantly to 23.9% with initial C:N of culture increased to 92.7.

BACKGROUND

Upscaling microbial fuel cells (MFCs) to make them energy-competitive systems requires a systematic understanding of their operating conditions. This study emphasizes the operation of a new MFC design with two gas diffusion cathodes under three different operational modes (batch mode (MFC-BM), semi-continuous mode (MFC-SCM) and continuous mode (MFC-CM)), towards increasing the power density, substrate utilization, bioelectrochemical kinetics and energy conversion efficiencies.

RESULTS

Higher power density was recorded with MFC-SCM (20.54 mW m−2) followed by MFC-CM (17.22 mW m−2) and MFC-BM (0.75 mW m−2). Such power density magnitudes were obtained with high anode projected surface area 220 cm2, which is about 10–100 times larger than frequently used in laboratory-scale MFCs. On the contrary, susbtrate utilization was higher with MFC-BM (91–96%) followed by MFC-SCM (74–84%) and MFC-CM (53–81%). A higher coulombic efficiency (CE) was obtained with the MFC-CM (7.5–11.2%), followed by MFC-SCM (5.4–5.6%) and MFC-BM (0.5–4%). This is of interest due to its dependence on both current generation as well as substrate utilization. Cyclic voltammograms along with derived bioelectro-kinetic parameters, i.e. redox Tafel's slopes (βa/βc) and electron transfer co-efficients (αa/αc), also explained the higher performance of MFC-CM and MFC-SCM.

BACKGROUND

Sulfonated poly (ether ether ketone) (SPEEK) membranes and their modifications are viewed as arguably the most promising in microbial fuel cell (MFC) applications due to their non-fluorinated base, superior chemical stability, and lower costs compared with Nafion membranes. In this work, SPEEK membranes with different degrees of sulfonation (DSs) (60% to 76%) and blended with charged surface modifying macromolecule (cSMM) were used as electrolytes in an MFC for simultaneous electricity generation and wastewater treatment.

RESULTS

Performance evaluation of newly fabricated membranes was carried out and was compared with that of Nafion 117. The MFC with SPEEK76/cSMM generated about 16.5% higher maximum power density (172.1 mW m−2) than that with Nafion 117 (143.7 mW m−2). In addition, the SPEEK76/cSMM exhibited the highest coulombic efficiency (CE) of 17.6%, which was 21.6% higher than that of Nafion 117 (13.8%). Chemical oxygen demand (COD) removal of all characterized membranes was above 80% in our particular MFC.

BACKGROUND

Lactic acid is an important biorefinery platform chemical. The use of thermophilic amylolytic microorganisms to produce lactic acid by fermentation constitutes an efficient strategy to reduce operating costs, including raw materials and sterilization costs.

RESULTS

A process for the thermophilic production of lactic acid by Geobacillus stearothermophilus directly from potato starch was characterized and optimized. Geobacillus stearothermophilus DSM 494 was selected out of 12 strains screened for amylolytic activity and the ability to form lactic acid as the major product of the anaerobic metabolism. In total more than 30 batches at 3–l scale were run at 60 °C under non-sterile conditions. The process developed produced 37 g L−1 optically pure (98%) L-lactic acid in 20 h from 50 g L−1 raw potato starch. As co-metabolites smaller amounts (<7% w/v) of acetate, formate and ethanol were formed. Yields of lactic acid increased from 66% to 81% when potato residues from food processing were used as a starchy substrate in place of raw potato starch.

BACKGROUND

Recent studies have characterized the most effective absorbent polymers for the removal of volatile hydrophobic pollutants from air. This study evaluates the performance of a laboratory scale α-pinene-degrading biotrickling filter (BTF) packed with lava rock. A second solid phase, Hytrel® G3548L (5%, v/v), was added in order to check its effect on the performance of the system during long-term operation.

RESULTS

The biodegradation profile was similar in both bioreactor configurations, with or without solid polymers, reaching a maximum elimination capacity (ECmax) around 25.6 g m−3 h−1 when an inlet loading rate of 57.2 g m−3 h−1 was applied. Tracer studies were carried out in order to determine the effect of the liquid and gas velocities, and to analyze the gas distribution with the different packing materials.

BACKGROUND

Pervaporation (PV) is a prospective industrial process for the separation of liquid mixtures such as azeotropic and close-boiling point. PV efficiency depends mainly on the properties of the membrane used. Hence, designing a membrane structure with high permeation rate and separation factor is an important issue.

BACKGROUND

The synthesis and application of novel Au nanostructures are of increasing importance in modern nanotechnology.

RESULTS

Closely packed and chemically difficult-to-synthesize Au nanohorns (AuNHs) were synthesized in the presence of Escherichia coli cells (ECCs) and hexadecyltrimethylammonium chloride (CTAC) by a microorganism-mediated, CTAC-directed (MCD) approach. A proper ECC dosage, ascorbic acid (AA) and CTAC concentrations were essential for the growth of the AuNHs. In the formation mechanism of the AuNHs the ECCs surface acted as a platform for preferential nucleation and initial anisotropic growth of Au nanocrystals. As a result, some of the adjacent nanoparticles over the cell surface connected together via linear fusion to form dendritic nanostructures. Meanwhile, secondary nucleation in the solution gave rise to smaller nanoparticles that were consumed later on via Ostwald ripening during the formation of the AuNHs. Eventually, the two-dimensional film-like nanostructures between adjacent cells easily connected to form well-defined AuNHs with three-dimensional nanostructures. Interestingly, the AuNH/ECC composites can be used directly as sensitive surface-enhanced Raman spectroscopy (SERS) substrates for effective detection of 4-mercaptobenzoic acid (MBA).

BACKGROUND

Solvent displacement crystallization (SDC) provides an energy-efficient alternative to evaporative crystallization potentially leading to crystal products of superior quality, both in terms of purity and size, due to better supersaturation control. The present work investigates the SDC process in terms of appropriate organic solvent selection and application to several metal (K+, Na+, Mg2+ Fe2+, Cu2+, Ni2+, Co2+, Zn2+, Fe3+ and Al3+) sulfate and chloride systems of hydrometallurgical interest.

RESULTS

Criteria for the screening of organic compounds with suitable physical and chemical properties have been established and 2-propanol was selected as an effective salting out agent to precipitate crystalline metal sulfates of practical interest; differences in crystallization behaviour among the various salts were linked to the hydration energy of the cation. None of the tested metal chlorides could be successfully separated, due to enhanced metal chloride solubility in non-aqueous solvents relative to water by formation of chloro-complexes with larger stability constants.

BACKGROUND

In China, soil pollution is becoming more and more serious with the national economy rapidly developing. How to remedy soil containing heavy metals in an effective and low cost way is increasingly becoming an urgent problem. Utilization of renewable photovoltaic energy in the environmental protection field brings forward a solution.

RESULTS

Cr(VI) removal from soil using an electrokinetic remediation process powered by photovoltaic solar modules and a DC–DC converter was studied. The results show that under solar irradiation intensity of 650 ± 20 W m−2 and 9 V output voltage of the converter, Cr(VI) removal efficiency of an iron electrode can increase to 99.8% in 30 min. For output voltage in the range 3–11.5 V, voltage has a significant effect on Cr(VI) removal efficiency. When initial Cr(VI) concentration is increased from 200 mg kg−1 to 450 mg kg−1, Cr(VI) removal efficiency and removal rate decrease. Total Cr concentrations and XRD analysis show that chromium in soil is accumulated near the anodic zone after electrokinetic remediation. For the highest voltage of 11.5 V, although sunlight utilization efficiency is the highest, electric energy consumption is the largest, and EPV and EPM are 249.4 kWh kg−1 and 156.1 kWh m−3, respectively.

BACKGROUND

Using persulfate in an advanced oxidation process to degrade organic pollutants has gained more attention in recent years. In this study, an ultraviolet activated persulfate oxidation process used to degrade carbamazepine (CBZ) in aqueous solution was investigated. The effect of persulfate dosage, pH, inorganic anions and humic acid on the degradation of CBZ was determined. In addition, the transformation intermediates produced during the process were identified using gas chromatograph–mass spectrometry (GC-MS). Photobacteria were used to evaluate the toxicity of the transformation products.

RESULTS

The results showed that the degradation efficiency increased with increasing persulfate dosage but decreased with the addition of Cl− and NO3−. Acidic conditions were more suitable for the treatment. Sulfate radical was identified to be the predominant radical in the oxidation process when the solution pH was not adjusted. Several compounds including 10, 11-epoxycarbamazepine, acridine-9-carbaldehyde, acridine and other low molecular compounds were identified. A possible degradation pathway was also proposed. Acute toxicity tests indicated that the inhibition ratio decreased from 100% to 65% in 60 min, illustrating that the toxicity significantly decreased with the degradation of CBZ.

BACKGROUND

The physicochemical stress-induced bioprocess is an efficient strategy for enhancement of the production of microbial metabolites, but multiple physicochemical stresses have not applied in poly-γ-glutamic acid (γ-PGA) production.

RESULTS

The effects of multiple physicochemical stresses on the production and synthetase genes transcription of γ-PGA were investigated in Bacillus licheniformis WX-02. Under heat stress stimulated at 50 °C, osmotic stress induced by 3% KCl, and alkaline stress mediated by pH 8.5, γ-PGA yields increased by 66%, 106% and 133%, respectively, and the transcription levels of γ-PGA synthetase gene PgsC were improved 3.1-fold, 3.6-fold and 5.4-fold compared with the control. Heat and osmotic stress also induced the up-regulation of another γ-PGA synthetase gene of PgsB with 1.4-fold and 4.3-fold increase, respectively. By combined application of heat and pH stress, the maximum γ-PGA yield reached 29.34 g L−1, 185% higher than the control.

BACKGROUND

Waste printed circuit boards (PCBs) are solid hazardous materials and may pose serious problems to the environment and human health. Bioleaching has been used to recover metal from waste PCBs. This study aims to isolate an effective Acidithiobacillus ferrooxidans strain and investigate its bioleaching mechanism during the process.

RESULTS

An A. ferrooxidans strain Z1 with average 0.2307 g L−1 h−1 ferrous ion oxidation rate was isolated from self-prepared mixed culture of acidophilic bacteria. After 7 days, 96% of the copper was extracted from metal concentrates by A. ferrooxidans at an initial Fe2+ concentration of 12 g L−1. Protons produced by the ionization of sulfuric acid and the hydrolysis Fe3+ played only a slight role in the extraction of copper. Dialysis bag experiments show 81.43% of copper was leached out by bioleaching without dialysis bag compared with 47.90% in the encapsulated bioleaching system.

BACKGROUND

This study attempts to elucidate the complex effect of Ca2+, an important divalent cation widely present in aqueous media, on perchlorate removal by autotrophic perchlorate reducing bacteria (PRB) associated with a zero-valent iron (ZVI) system.

RESULTS

Batch flask test results showed that, in the presence of larger amounts of Ca2+, perchlorate removal initiated earlier and completed faster. According to the increase of differential chloride concentration, the respective contribution of biodegradation to perchlorate removal was evaluated and found to be improved with increasing amount of Ca2+. It appears that Ca2+ can delay pH increase by combining with OH− and can consequently extend biodegradation time. Despite the major contribution of biodegradation, when ZVI and Ca2+ co-existed, physiochemical perchlorate removal occurred earlier by both adsorption via surface charge neutralization and co-precipitation via formation of larger particles. The positive effect of Ca2+ was further evidenced in subsequent continuous column tests. As empty bed residence time (EBRT) was decreased, more reliable and effective perchlorate removal performance was observed with additional Ca2+ concentration of 240 mg L−1.

BACKGROUND

Flue gas as carbon source for microalgae culture has been applied to reduce the high cost of production. However, low mass transfer efficiency owing to the low CO2 partial pressure in flue gas limited its utilization. In this work, monoethanolamine was proposed to enhance CO2 utilization and microalgal biomass production.

RESULTS

In abiotic absorption experiments, the total inorganic carbon concentration in the medium increased with the increase of monoethanolamine concentration and the CO2 absorptivity remained above 60% for a considerable pH range (6.5–10.0). The biomass productivity and lipid productivity of Scenedesmus dimorphus were enhanced with monoethanolamine ranging from 0 to 100 mg L−1. When 100 mg L−1 monoethanolamine was added, the CO2 utilization efficiency reached 76.1%, which was much higher than the 44.5% obtained in routine culture. The growth of cells was inhibited with monoethanolamine concentration exceeding 150 mg L−1. The changes of net photosynthetic activity revealed that the oxygen evolving complex might be injured by the higher concentration of monoethanolamine.

BACKGROUND

Horseradish peroxidase (HRP) is a peroxidase-type enzyme containing heme as prosthetic group. It is a versatile enzyme that has been used for detection of H2O2. New supports for immobilization based on nanomaterials have demonstrated ideal characteristics for maintaining enzyme stability, offering many advantages over conventional immobilization supports. Titanate nanostructures show attractive properties for this application.

BACKGROUND

The effluent from pulp and paper mills is difficult to treat effectively via conventional biochemical processes due to the high concentration of lignin and its derivatives. In this study, the integration of electrochemical oxidation and biodegradation (EO-BD) for Kraft lignin (KL) was proposed to potentially enhance the efficiency of the treatment. Typical anodes, titanium based antimony doped tin dioxide electrodes (Ti/Sb-SnO2), were used in the pre-degradation of KL solution (1000 mg L−1), followed by post-biodegradation using aerobic flora as inocula. Response surface methodology (RSM) was applied to optimize the EO-BD of KL.

RESULTS

The optimum conditions obtained via RSM were: current density 3.68 mA cm−2, electric quantity 14.49 kC and pH 9.0. Under these conditions, the maximum chemical oxygen demand (COD) removal rate and minimum specific energy consumption were predicted by the correlation developed to be 70.83% and 28.84 kWh kg−1 COD, respectively, which agreed well with the experimental data. The results of gas chromatography–mass spectrometry (GC-MS) analysis indicated that KL was partially degraded by EO, which was beneficial to the subsequent biodegradation.

BACKGROUND

A modified Fenton reaction was used for the remediation of a soil polluted with ethylbenzene (EB), a toxic compound in gasoline. Fe(III) and trisodium citrate were used as catalyst and chelating agent, respectively. pH remained near-neutral during the process. Contaminant, chelating agent, oxidant and iron in solution were monitored at all times. A comparison between slurry (aqueous-organic and soil phases) and liquid systems (aqueous-organic phases) was carried out.

RESULTS

EB conversion increased as H2O2/EB ratios rose, for a given EB concentration. Furthermore, the contaminant conversion was decreased as the EB concentration increased, at a fixed H2O2/EB ratio. This indicates that the reaction takes place in the aqueous phase, with the oxidation rate limited by the EB concentration in this phase. The presence of soil produces a better contact between phases, enhancing EB transport from the organic to the aqueous phase. As EB was oxidized in the aqueous phase, the toxicity of this phase decreased, because non-toxic oxidation byproducts were obtained. The chelant was oxidized, but not totally mineralized. This chelant oxidation produces precipitation of the catalyst from the aqueous phase.

BACKGROUND

To remove toluene (a representative volatile organic compound (VOC)) from a waste gas stream, catalytic oxidation was utilized over Cu/Clinoptilolite–CeO2 nanocatalyst. The nanocatalyst with different loadings of Cu (5, 10, 15 wt%) was sonochemically synthesized and its performance in catalytic oxidation of toluene was studied. Characterization by XRD, FESEM, BET, EDX and FTIR were applied.

RESULTS

XRD results indicated well-dispersed small copper particles even at high loadings of copper. Non-sonicated Cu/Clinoptilolite–CeO2 catalyst showed agglomerated, non-uniform morphology, while small particles with uniform shape and size with different degrees of agglomeration were observed in sonicated Cu/Clinoptilolite–CeO2 catalyst. A narrow particle size distribution with average size 21 nm was observed in the sonicated sample. BET analysis demonstrated considerable effects of HCl treatment in increasing the specific surface area of clinoptilolite. It also showed the strong influence of CeO2 addition as a promoter that sharply enhanced the surface area to 71.7 m2 g−1.